A common complaint about the old school renaissance is that it's too "D&D-centric," the unsaid implication being in many cases that either a) there's not an interest in old school gaming broadly conceived and therefore no one should pay the OSR any heed or b) there's an active effort to restrict discussion of old school gaming just to D&D, because "old school" only makes sense in that context (and we're a bunch of meanies who hate everything that isn't D&D).
To this complaint I can only offer two related observations. First, I regularly post about games other than D&D and, with very few exceptions, those posts garner significantly fewer comments and views than D&D-related ones. Second, I don't think this is at all odd, given that, now as then, Dungeons & Dragons remains the proverbial 800-lb. gorilla of the hobby. It's the game most people play (or have played) and so naturally generates far more interest than, say, Stormbringer or Space Opera or whatever other old school RPG I'm keen to talk about on any given day. There's neither a conspiracy nor blinders at work here, only reality.
I'll add here that I think that many, though not all, of the complaints come from folks who aren't actually paying much attention to the current state of the old school renaissance. There are quite a few new old school games in the works right now, as well as a couple that are already available, like Kevin Crawford's awesome Stars Without Number, that reveal an interest in both old school themes and, more importantly, design principles beyond the creation of yet another D&D retro-clone. Likewise, blogs and forums devoted primarily to non-D&D old school RPGs, such as Tunnels & Trolls, RuneQuest, and Villains & Vigilantes, to cite just three obvious ones, are starting to pop up all over the place. That's a good thing in my opinion and, while the expansion of the OSR beyond D&D might be slower and less impressive than some might wish, it is occurring and I fully expect it to continue to do so in the years to come.