Um, really, PC gaming means windows. Just because id software (plus, admittedly, a large portion of the indie gaming community) likes *nix doesn't mean other game companies will follow suit. It's about market share and making money: the *nix market is a) small and b) full of geeks. The b) makes for an excellent market, but a) makes it just not worthwhile to spend time and money programming games for it.
Wine is emulation, and emulation is slow (and, often, slightly buggy). (YMMV, I've never actually used Wine, void where prohibited.) Even if *nix is faster than Windows (which is quite possible, depending upon the build and options of each system), that emulation layer slows it down, so the hottest *nix gaming system will be slower than the hottest Windows gaming system---for the majority of games on the market today.
id software is rather cool for releasing *nix versions of their software, yes---but they're also in the minority. It's mostly a pleasant coincidence that a major company dedicated to *nix releases also happens to produce high-quality, popular games.