Of all the misconceptions surrounding the release of 4e, I think the "AD&D conventions are the same as literary fantasy conventions" is the most insidiously annoying.
D&D has never been representative of anything but itself. Gygax and company threw in a lot of Poul Anderson, and lot of Jack Vance, some Robert E Howard, H P Lovecraft and Fritz Lieber, a bit of Lord Dunsany and Tolkein and a health dose of Greek, Norse, Mesoamerican and Asian mythology into a big pot, lit a fire under it and stirred it up. The brew they served up from that pot was not "classic fantasy" or classic anything else but classic D&D.
D&D is our game, we can add to, remove from or otherwise tweak the "classic D&D conventions" anyway we like, and obviously if we can, so can WotC. If you don't like the changes they made, that's fine, but it's just not a valid criticism to complain abut the lack of tieflings or dragonborn in fantasy literature as a reason for WotC to exclude them from D&D