Maybe because he didn't become famous. Just in the game, and not inthe Stars Wars "official" universe like you said. Just my guess. Or it's just too hard to make a character that won't upset everybody but a few.
I mean, everybody has his/her own Revan made up in their minds. So they chose not to make Revan official like thay did with Malak.
Personally, i wouldn't mind how they made Revan as long as he gets a site just like Malak, he deserves it much more than Malak does.