Maybe they did, but I remember it being pretty awful before they raised the age limit. Every year we would sweat out whether our top commits were going to decide to go pro right before the draft deadline. It left teams in a bad situation where the best solution was to try and steal a recruit away from another school, else wise you have a hole in your line up that can affect the make up of the team for more than a year.
I agree with you - let them enter the draft or play in the G league or go overseas. If they're talented enough and determined enough they can succeed. If not they can say they gave it their best shot. But i truly believe that a year or two in the NCAA will market you to the NBA draft better than anything else. Unless your name is Lebron James.