Nope. It's not too far out. If non-Tolkien-esque races were a deal breaker for the public, then Runequest with its Ducks, Jack Vance's Dying Earth with its Pelgranes, Buffy with its 'good' demons, Farscape with its amphibious, diminutive, multi-stomached, deposed monarchs and so forth would have utterly failed to capture an audience. As it turns out, it seems that most people want more 'new' and 'different', rather than more of 'the same old thing'
See J. to me, you're exactly right in a sense. None of these, except Buffy, were particularly successful with "the public". Runequest, whilst allegedly "challenging D&D" in sales at some unknown point in the '80s is pretty much a footnote in RPG history with absolutely zero presence in the "public consciousness" (and hell, not that much presence in the RPG player consciousness!) and, I would suggest, little to know appeal to a casual fantasy reader or viewer. Similarly, the Dying Earth books, whilst classics, are not well-known outside of specialist sci-fi/fantasy circles, and not well-read. Farscape was reasonable successful, I agree, but that's science-fantasy, which I think appeals to a rather different selection of people. Not that they're not worth appealling to, but I do think it's success was more of a "Star Wars" deal than a "LotRO" deal, as it were.
None of the properties you mention remotely compare to the success of more "standard" fantasy (with humans firmly at the center, other races peripheral at best), such as LotRO, Harry Potter, Narnia and Pirates of the Carribean. In TV, Buffy has humans firmly at the center again, with just vampires (who are essentially humans) and the odd demon or semi-demon (most of whom either act or look completely human, and certainly don't have alien cultures or the like). Sci-fi can go both ways, though I suspect human-o-centric stuff like Stargate or BSG is generally more successful than Farscape or Babylon 5 (indeed we know it is). Still, maybe Star Trek can be argued to the contrary (Star Wars is harder to, have only the Droids and Yoda as major non-human characters - the other non-humans are largely scenery).
Don't get me wrong. I'm not telling D&D what to do, but I do personally think that by going the "out there" route, towards sort of '70s fantasy imagery (floating mountains, everything is epic and glowing and so on) and near-Farscape (one of my favourite shows ever btw) levels of non-human-ness, they're directing themselves very much towards a "gamer-ish" audience, and completely ignoring a larger audience who are interested in fantasy, but not into this whole "ROCKIN' FAR-OUT FANTASY DUUUUUDES!" deal that for me, 4E seems to have.
Maybe that's the right decision. Or maybe they have plans for a non-D&D FRPG to reach out to the HP/Narnia/LotRO/human-o-centric literary fantasy audience. Certainly there's a whole generation of kids out there, growing up on fantasy via the above films/books (and Spiderwick etc.), but very much not the kind of fantasy 4E is full of. Perhaps this is what 5E will be about.
No other "core" race in 2E got treated as badly as the gnomes did.
GNOME POWER! <does gnome power salute>
I mean what...?
You're writing like they have some kind of "duty" to a particularly insipid fantasy game race. They don't. If gnomes don't innately "cut it", it's totally righteous to kick them to the curb. It's not treating them badly, it's being rational and reflecting what your customers want.