I think Pitino said it best that the NBA's age limit is more for the NBA than the NCAA. NCAA doesn't profit much from a bunch of one year and out players. It's not worth it, no college wants those players.
NCAA benefits far more. They get the Kobe's, TMacs and Garnetts. You think college basketball wouldnt have been excited as hell to have Dorrell Wright, JR Smith and Josh Smith even if it's for one year? Then you get guys like Rudy Gay who really only plan on staying for one year but find out they like it and stay for a 2nd. NCAA gets the best HS players, that is a huge win for them. Sure the age limit stops the HSers, who lately havent even had the waiting period to produce, but NCAA is the huge winner. Just look at the hype that Greg Oden is creating or imagine if Bron was playing a year in college. It will also help to create more parity in college basketball. All of a sudden the very top players go to Duke and co and the guys that would have gone to them when those guys got drafted go to the next level teams. Basically Duke still gets the best players but they only stay for a year.