User blog comment:ForestFairy/How Internationalization Works at Wikia/@comment-28369736-20160804102423/@comment-20644-20160804220154

We would prefer to let individual communities decide which version of English to go with. For example, Doctor Who Wiki uses British English because it's a series based in the UK. Wookieepedia, on the other hand, uses American spelling because Star Wars is made and published in the United States, and thus Star Wars uses American English. Though on the flipside, Star Wars also uses "kilometers" instead of "miles," so Wookieepedia follows suit.

So rather than having starwars.wikia.com and uk.starwars.wikia.com, for example, which would largely be duplicative efforts, it's generally best for each English community to make whatever decision is most appropriate for them and their fandom/subject matter.