Ratskinner
Adventurer
The problem is that D&D does generic fantasy pretty badly. It does 'D&D style fantasy' (which at this point I think qualifies as it's own genre) to the exclusion of all else - and a lot of those things get in the way of generic fantasy.
Unlike some people, I think that's a pretty good thing. In some respects I agree with the OP, regardless of their intentions, in that I think emphasizing the unique D&Disms/IP (i.e. illithids, the Gith etc etc) is the best way forward for D&D.
And please, if there's to be a default setting for the next edition, make it something NEW already. The last new thing D&D did, setting-wise was Eberron and that was in what, 2004? EIGHT years ago?
Personally, I'm hoping that 5e with all its knobs and buttons will be able to do a broader swath of "generic fantasy" than its predecessors. When it comes to published settings...I'm starting to feel like Magic should be the model. Crank out a new setting with adventures each and every year. If one is crazy popular, revisit it in 5 years.