What I'd like to see more of are books where the material is all brand new. Stuff like Races of Stone and such are simple expansions of existing rules and supplemental stuff. D20 Modern was all-new as was D20 Future. Deities & Demigods is another example. Libris Mortis and Draconomicon, while expansions, had enough interesting new stuff to fall into this group because of the broad multi-use things within.
Racial books, though, and things like Savage Species and Stormwrack, just don't provide enough frequently usable new territory.
Like I said, it's just a concern for the time being. Still, some things like the Planar Handbook even have me quite nervous as to the direction.