Perhaps I am in the minority, but I believe that 3rd edition and the OGL gave us an awesome and powerful engine with which to run a role playing game. We were given a golden opportunity to tell a variety of exciting stories in several customizable ways. The modular nature of the system and its focus on a unified mechanic has proven to be a stable breeding ground for innovation and creativity. A plethora of source material has resulted.
Is the majority of available material (both official and 3rd party) crap? Probably, but that's the case for most things in life. (Present company excluded...)
Haven't the various splat books broadened our perception of the rules? Have they not allowed us to tailor-fit our games with easily swappable content? With every new book, are we not allowed more freedom to run the game we want to run?
I say, bring on the splat! I'm an open-minded player and I try to be an open-minded DM. I like to have options at my disposal. I don't buy every book I lay my eyes on, nor would I want to. In that same vein, I don't allow every piece of material in my games, nor would I expect another DM to allow it in his/hers. There is no one holding a gun to our head.
As for the players that feel entitled to use every book they spend their hard-earned cash on... Well, it's not like most gamers aren't predisposed to wasting money. Furthermore, blowing money on source material you'll probably never use is a likely sign of a DM-in-the-making. Encourage them to run their own game. The world needs more DMs.
