Wow, it's great to see so much support on ENworld for Labyrinth Lord! It seems like the demographics are shifting a bit. I would have expected more votes for Castles & Crusades here.
I would guess that is for several reasons. One reason is that most who post over on the TLG boards say they don't come here anymore, or never came to ENWorld to begin with.
Plus C&C is not "old school", for example I know a lot of the "old schoolers" in this very thread wouldn't accept my C&C as being old school simply because of how many house rules I have stolen from 3E and 4E. Plus I am not the only one to do so, I know there are dozens of C&Cers who take house rules from 3E and 4E more than any other edition.
So combine that with the fact that C&C uses ascending AC and a unified d20 mechanic, C&C is far more modern than old school. We make our C&C old school by using monsters, magic items, and spell versions from our RC's, 1E DMG's, etc...
Plus there are a fair number of us who started with 3E, I have been surprised with how many who have posted. chatted, or SKYPEd with me who never played before 3E.
Still, bottom line is that C&C isn't defined or accepted as "old school" by many.
The only reason I call it old school is because of how simple it is to run. So it reminds me of the simplicity of all the old school games.