Because the quality of player entering the NBA isnt as good or polished as it was back in the 90s. And a lot of college coaches want it to. As a college hoops fan I'd love it, the great Duke teams or the great UNLV teams where you knew for multiple seasons that guys would be coming back where much more fun than a Kentucky who I couldnt name more than 1 player on for much of the year.

I'd be just fine with a system that allowed kids to go pro after HS and work their way up through the D league or if they went to college be ineligible for the draft for a number of years.