I see no particular reason not to, if it's the case (which I don't know) that a significant number of people communicate largely in Singlish and find it more natural than "standard English". We already have a ht.wikipedia.org for the Haitian creole, which is basically a French dialect with significant influences from a number of African languages. For a long time it was considered basically "improper French", and people spoke it but didn't write it---indeed, writing in it would earn you an F on your essay in school. More recently, that's been recognized as a sort of cultural elitism, and it's becoming recognized as an acceptable language to write in, and in fact the standard language of Haiti.
It might be worth pointing out that "standard English" for Wikipedia's purposes is itself already different from what your English teacher might say is standard. We tend to avoid (for the most part) not only local dialects that are "improper" but also avoid "proper English" that is not commonly used, or is only used in some regions of the world.
This is in some sense basically the [[en:Prescription and description]] debate. Should we be enforcing handed-down rules of "correct language", whatever that might mean, or should we merely be documenting language as it is actually used by real people?
(Of course, whether written Cantonese and Singlish are used by many people or not is another issue. I'm just arguing that the fact that the Chinese and Singaporean governments dislike them and consider them "improper" shouldn't be the deciding factor.)
I cannot agree with you. I agree that we should not use "proper English" that no one today understands. But if we accept languages that are not commonly used in formal writings, we bear a danger of undermining the credibility of Wikipedia, and credibility is one of the most important considerations for readers.
Wikipedia has long been doubted for its credibility. I personally do not agree with the view that Wikipedia cannot be trusted because everybody can edit. I have this trust in Wikipedia because since I discovered Wikipedia I have always seen it as a serious effort to build an encyclopedia, despite its unconventional way to writing it. But if I am told today, that Wikipedia has a version written in Singlish or Cantonese or other spoken languages that are rarely or even never used in formal writings and academic discussions, I will begin to doubt if the aim of the Wikipedia is serious and its goal is to build a trustworthy encyclopedia. And this in turn will undermine my confidence in the credibility of Wikipedia.
Singlish, like Cantonese, are widely used in informal dialogues and writings. But it not "natural" for Singaporeans or Hong Kongers to write formal essays using Singlish or Cantonese, and neither are they accustomed to read any formal written works (such as an encyclopedia) that are published in languages that they think should only occur in daily conversations.
formulax