[Sal the Mudokon]

Well, for starters, it'd be too complicated. Not too complicated to understand, but too complicated to the average gamer, who wants to pick up a game and play it... not spend alot of time learning calls in a non-existant language. Tolkien: Yes. Oddworld: No. Star Wars: Brit's in space? And about the English thing in general (being the American version that I played) adds to the earth-like mystique. But in a way, the natives DID have their own language, a code language made up of whistle (and farts) to help connect muds together. The sligs, scrabs, paramites, and other creatures had their own native forms of communication, but the Glukkons (as far as we know) only speak English, adding to their connection to Earth.