One and done NBA here I come the down side.?

Everyone is talking OJ Mayo and his bad choices to take money and properly opening USC up to NCAA investigations,but the problem started when high schooler's was told that they had to attend one year of college before going to the NBA ,because Brand and Stern was concern about the quality of college basketball ,before that all player that didn't want to stay went pro ,why don't colleges do better job scouting players and recruiting the players that will stay and stop putting colleges in this spot. If a having a player for one year causes all this damages then what's the upside.