Who wants a bunch of one year and done players? That's not really helping the NCAA. Sure, it might get more competitive, but most likely those guys have no loyalty or commitment to the school. They're just there and then they're gone. For the players like Ndudi Ebi, Kwame, Dorrell Wright, it'll expose how unprepared they are for the league, which benefits the NBA not the NCAA.
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.
A program like Duke doesn't take on many one year and done players. The only player in recent memory is Loul Deng. Guys like Battier, Boozer, Jay Williams, Mike Dunleavy, Ewing, Redick, Shelden, Paulus, McRoberts etc have all stayed for most of their college careers. Which leads me to believe that all those one year players won't be recruited by Duke or any university that is trying to bolster their reputation with committed and loyal players, not the ones who are trying to use the college.
In the end, the rule is there for the NBA. It's basically helping the 30 teams with their scouting by forcing players to play at a bigger stage and to see if they're ready or not. Stern has seen so many wasted draft picks that he's there to help the crappy teams, who tend more to pick the high schoolers with lotto picks.