Hah! I thought my proclamation of a somewhat radical taste had killed the thread! Nice to see that there's at least a little life left.
First off, I'd argue that of those four, only two are popular: elves and dwarves. Gnomes and halflings get relatively little love, and gnomes in particular only play to either players with esoteric tastes, or characters of an esoteric nature. Reading between the lines, it seemed apparent to me that WotC agreed with me at the launch of 4e, since the gnome was not a player character option at first.
But far and away the most popular character type, in my own personal experience and in polls that I've read here and elsewhere--at least since the launch of 3e, if not before--is human. Not only that, except for Lord of the Rings (and books that are to a greater or lesser degree a pastiche of Lord of the Rings--stuff by Fiest or McKiernan, for instance) and D&D or Warhammer fiction, the assumption of elves and dwarves is not normal in fantasy fiction. Especially the kind that I read, which more and more is drifting into non-traditional molds. In other words, the elfs, dwarfs, gnomes and halflings of D&D are something that really is specific and unique to D&D and have little or no analog between the covers of the very same fantasy literature that inspired the game--excepting Tolkien, of course.
Now, granted--D&D isn't necessarily supposed to emulate fantasy fiction, and some folks would say that that's not the point, and that's not a problem. But for me, and I suspect a number of other gamers who came into the hobby through the same vector as me, the whole point of playing D&D, the whole reason that it was an attractive idea as a hobby in the first place, was because of our love of fantasy literature. What made the game sound like fun was being able to be involved more intimately in an experience that was not unlike a collaborative and semi-improvisational fantasy literature experience. As such, many of the disconnects between D&D and fantasy literature (speaking of the genre generically, of course, since obviously there's a lot of variety in setting, tone and feel amongst fantasy literature) got to be more and more grating and frustrating over time. In my case, it led to me leaving D&D entirely in the late-middle 80s over "creative differences" and I played some other games for a while before getting too busy to really game at all. Sometime in the mid-90s, I started poking my head back in the hobby again, checking out what was on the shelves at stores, and stuff like that. Around this time, White Wolf was at their heyday, and for a little while, I was captivated by the high concept of those games. That didn't last all that long, but it did manage to bring me back into the fold as a gamer, at least.
When 3e was released, I was ready to embrace more traditional fantasy again, and since the game was flexible enough to allow me to play the games I wanted to, I became specifically a D&D player again, and an enthusiastic one at that. But before long, the same issues that I had before started to grate against me again, and I felt more and more like D&D was a subgenre of fantasy unto itself that bore little relationship to anything else in the genre that wasn't specifically D&D already. So, again, I started casting my eyes about at what else was going on.
This time around, I had come to peace with the rules, at least--for the most part--and part of that was the flexibility inherent in all the various modular subsystems that were developed for other d20 games, or in Unearthed Arcana or by third parties who had developed new magic, new races, new classes, etc. So rather than ditch D&D for some other game--like Savage Worlds, for instance, which I suspect would be right up my alley if I ever got into it--I just houseruled the game more to my liking.
In the case of the races specifically, I came to associate them quite strongly with the D&D paradigm which I was rejecting. Luckily for me, I probably have literally hundreds of other racial options in print from one source or another, so I was able to give potential players in my campaign other options. Curiously, I ended up literally homebrewing most of my races myself rather than using ones in print, although there are some obvious similarities between some of mine and some that are more familiar. So for my setting, I have:
- Humans. Still the baseline, as in D&D.
- Azhar from the d20 Freeport setting. Conceptually, they are not far removed from an LA+0 fire genasi, though. I call mine jann, re-imagined them visually (based with Red Men from Barsoom, actually, with a bit more "fiery" details) but use them mechanically as is.
- Another race that takes the azhar and gives it a more darkness/shadow twist rather than fire twist, but otherwise is built off the same mechanical "chassis." Visually, I imagined these guys as a hybrid between Nightcrawler of the X-men and Darth Maul. They have some obvious similarities to tieflings, so I even adopted a kinda sorta Bael Turath analog for their backstory too.
- Changelings are a custom-mechanics race, based loosely on the half-orc, but given a more wildman approach. Although I frequently say that they're based on the wildman/wose archetype from medieval heraldry, art and folklore, in reality they're probably more based on the shifters from Eberron and the tharn from Iron Kingdoms than anything else.
- Neanderthals from Frostburn are adopted pretty much exactly as is. Plus, everyone knows what a Neanderthal is, right?
- Although I've since decided that this is just another human culture after all, I also had a goblinoid empire, and made hobgoblins and goblins specifically PC choices in an earlier iteration of my setting. I kept everything except the mechanics--like I said, it's now just a somewhat exotic human culture rather than humanoid. I do maintain gnolls amongst this group, but rather than a separate race, it's a magical transformation that individuals can undergo to become elite shocktroops of this race's harsh and militaristic state religion.
- Not really a PC option, but vampires play a significant role in my setting too.