If there is one thing which Wikipedia ought to be, in terms of gender, race, religion (or absence thereof), sexual orientation, philosophy, etc, it is that it ought to be a very open and embracing community. There are a number of very strong and cogent reasons for this. The central idea of Wikipedia is that it makes information available to everyone, without exception, and without cost. Similarly, given that everyone, from every section of society, is a potential consumer of the information represented in Wikipedia, it is fairly obvious that the broad diversities of society, both mainstream and minority should be empowered to represent their perspectives equitably and objectively within the body of knowledge whilst striving for the ultimate desideratum, the Neutral Point of View (NPOV), of which much more later.
Diversity and inclusiveness of the community in terms of the editor base are quantitative and qualitative measures of the overall health of the community. A considerable amount of work in this respect has already been done by the Task Force Quality group and the Community Health issues group also recognise that this is an important area of concern which needs to be addressed and resolved, and as being of high importance.
Diversity of Editors = Good
The diversity of the editor base is a very useful component in ensuring continuity of one of the central tenets of Wikipedia which is that it operates, or at least endeavours to operate, from the position of NPOV. Much has already been written on this subject and it must be taken as a given that all edits should conform, or try to conform, to this perspective. It is a sad fact that almost ten years since the inception of Wikipedia, very few do.
Reality, as ever, alas, intervenes even in the field of NPOV: one man's NPOV is another woman's misogyny. For this to be recognised and addressed you need to have women editing or with a voice to point it out. Moreover one woman's NPOV is potentially another woman's philosophical ambiguity. This all comes back and round to the oft-stated Open Source software principle, given enough eyeballs, all bugs are shallow. It would perhaps be helpful here to extend Eric Raymond's premise a little to qualify the remark so that it reads given enough eyeballs from a diversity of perspectives, all bugs are shallow.
Subjects, as a matter of course, tend not to attract dispassionate editors. They tend to attract editors who have a passion for or an engagement with them. Trainspotters tend to write on the minutiae of Class 666 locos, Amtrak's livery or whatever else it is that these consenting adults get up to in their spare time. Enthusiastic Christians tend naturally to the finer points of doctrines, the live of saints, the enduring fallout from the Albigensian heresy, etc, etc. This is only obvious and natural: the writing and editing of Wikipedia is, or at least used to be, fundamentally recreational. The upshot of this is that articles on Christianity and pertaining to areas specifically of Christian interest tend not to be written by largely dispassionate trainspotters and, of course, vice versa, to the inevitable detriment of the articles themselves.
The real victim here of people writing in an undetached and empassioned manner of subjects of interest of course is NPOV although this is not entirely downside, some articles prevail in their overall quality despite the obvious slantedness of the POV. Also, the occasional meeting of trainspotters and Christians in articles of mutual interest can have both predictable and unexpected consequences for the developmental outcome of the article which represents an area of mutual concern. The problem raises its head volubly above the parapet, when, for example, conflict arises between the trainspotters and the Christians on some fine or not so fine point of doctrine or railway ideology. From here it is but a short step to the depressingly well-documented battlegrounds in Wikipedia such as Kurdistan, Charles Darwin, Israel, and, in the case of trainspotters, the Personal Rapid Transport (PRT) page which has attracted external interest in that considerable organ of railway information, Light Rail Now! .
The PRT page  is actually an example of a page ripe in POV and fancruft which could well do with some love from members from outside the usual ambit of contributors. Consider the (as at current revision)leading statement from the Safety section. "Computer control is considered more reliable than drivers, and PRT designs should, like all public transit, be much safer than private motoring." Apart from a marked absence of contributions from members of the grammar-equipped minority, there is no indication of just who considers computer control to be more reliable than drivers. This is unquestionably POV; moreover it is speculative POV for which there is little or no corroborative evidence.
A more reasonable exemplification might read something like: A central argument presented for computer control is that it is predicted by some proponents of PRT to be safer than private motoring. However this fails the intelligibility test and the qualifying some hovers perilously close to weasel words, with which we cannot be doing. Let's have another try. In the opinion of advocates of PRT, computer control might prove to be safer than private motoring. Not a weasel word in sight other than that of the speculation itself, and a fairly dispassionate statement of the situation.
But this is to entirely miss the point. The point is that even cleaned up it is written from a fundamentally WASP male perspective and does not address questions which may reasonably be asked by people from a divergent viewpoint.
Despite the concluding paragraph As with many current transit systems, passenger safety concerns are likely to be addressed through CCTV monitoring, and communication with a central command center from which engineering or other assistance may be dispatched, a worried mother might still reasonably be concerned about little Johnny taking advantage of the availability of a PRT ride and taking off in it and subsequently becoming lost: CCTV is only useful after the fact (cf. the Jamie Bulger case). So Mrs X. might reasonably add the observation Critics argue that the direct absence of human intervention affords no protection to unaccompanied young children who may avail themselves of PRT and become detached from their parents. The fact that little Johnny probably succeeds in becoming lost with or without PRT is neither here nor there; it exposes a facet of safety which having technology as the primary determinant does not take into the equation and that there are safety risks which are not explicit in the software design itself. Wheelchair users will have a stake in this as well and ask questions about what happens if their wheelchair becomes stuck and having to wait in difficult circumstances for engineers to turn up, etc, what happens if the comms fail or there is a power outage, etc etc. At the moment though, safety (as far as the PRT article is concerned) is a set of tunnel vision assertions primarily concerned with collision avoidance. Only a very experienced editor on the lookout or people operating from divergent perspectives can bring this sort of broadening out and reflection of the real concerns to the table. This is as true in any article as this; the PRT is just a random example from about 2.9 million where more perspectives would bring real improvements.
Possible Ways to Grow Diversity of Editors
What do we need to do?
A focussed effort is required to ensure a general broadening of the editor base, and an empowerment of disengaged and largely unrepresented or under-represented minorities (or in the case of women, an under-represented majority). This is not going to be an easy problem to resolve.
In societal terms, what we possibly need is some form of positive discrimination in favour of edits which a) improve article quality, scope or reach and b) which extend the edits on articles away from the current self-selecting communities which control the ideology expressed in the content into the ambit of people who would not ordinarily edit those articles. T
This is not going to be an easy task to accomplish. We have somehow to find a way to draw in people from the under-represented sections of the wider community. Having got them here, we then have to protect and nurture them.
How do we do it?
One way we could do this (and I am winging this and am entirely prepared to be shot down in flames, this is an illustrative proposal to kickstart the debate) would be to have a lockdown on editing of the entirety of Wikipedia for a few days, with the exception of articles beginning with the letter 'Q' or the letter 'X', and the further proviso that no one can make edits to an article on which they have worked prior to the lockdown period. This would be an interesting experiment in its own right. We could further make an event of it and positively encourage new editors to contribute and for experienced editors to be tasked primarily with assisting the new editors.
A broadening of the editor base with a mandate to fix articles constuctively, with the ability to supervene the multi-faceted wikilawyering and edit by policy instruction, with an overarching instruction to ensure NPOV and article quality over above policy would see an erosion of the power and grasp of the cabals which see these articles as their exclusive territory. We need to increase and maintain not only the physical numbers of editors, but also, and possibly more importantly, the diversity of viewpoints, since this will do much to improve the overall quality of the articles in the medium to long term. We need to encourage and acquire the involvement of new editors, and particularly those from under-represented categories, and we need to find a way to nurture them, and not, as is currently the case, tag/speedy them away as fast as they create their first policy non-compliant venture into wikidom.
Unfortunately, one major obstacle to broadening the editor base is the fact that current editors provide over-representation to certain demographics; changes made to more accurately reflect reality may be deleted by current editors who are uncomfortable with the inclusion of views from female or non-white editors. Thus, it is important to not only encourage a more diverse group of editors to join the Wikipedia community, but to consider training for current editors so they recognize how their own biases and perspectives have led them to censor others' opinions, which has discouraged participation by new editors.
Encouraging New Editors and Fostering Diversity
Another option which could be considered is a separate fork of Wikipedia as a New Editor, New Articles (NENA) factory, with an associated recruitment drive, where new editors (from hopefully diverse backgrounds) could come to learn their trade with the help of experienced editor/mentors who could assist them in negotiating the notability and policy minefields (until these have been definitively rectified). Once the articles have reached a degree of maturity they can then be handed over to the mainstream Wikipedia, and the happy new editors can be armed with a certain degree of insight and understanding of how to deal effectively with the inevitable negative and contrary edits which will be winging their way in the live jungle. They could be encouraged within the ambit of NENA to build up a network of contacts and helpers to assist them, and their mentor relationships should also be looked on as a possible longer term relationship.