In working on the second volume of the Dwimmermount Codex, I often found myself poking around in the D&D III SRD, since there are some monsters and magic items in it that don't appear in other retro-clone products (at least so far as I am aware). What I discovered -- or, rather, was reminded of -- was just how much of the DNA of OD&D and AD&D made it into 3e. I'm not just talking about the ideas of those earlier editions; I'm also talking about the actual words used to present those ideas. For example, fireball is described as "detonat[ing] with a low roar," which is exactly how Gygax described it in the Players Handbook. I could cite dozens of other examples just like that.
Stuff like this is why, for all my many problems with 3e, I'm still grateful for the role it -- and the SRD/OGL combo -- played in preserving and transmitting the ideas and words of previous editions, for which every one of us involved in the old school community should be grateful. Were there not a strong family resemblance between D&D III and the TSR editions we all love, the creation of the retro-clones would have been that much harder to accomplish, perhaps even impossible. We've been given an amazing gift, one that only seems more amazing as the years wear on.