does it realy matter, why is there no elums in AE? because maybe it didn't suit the story, because there was no real point, because it was too hard technically (as others have said). so what if there is no rain in AE, buy a game with rain, as was said above, there is rain in SW, therefore there is rain in oddworld, end of story.
maybe I would have wanted rain in AE, but I don't have AE, and it is too late to add it in anyway, and it realy wouldn't do too much.