The root of this problem began with the "one and done" culture because it opened the door  for teenage boys to be bribed with money, shoe deals, access to "successful" agents and so on. The list is endless.  When college players stayed at a school for 4-years in the "old days" and were drafted after their senior year, the landscape was different. 

Likewise, paying athletes while they are in school will NOT CHANGE anything about the culture except give them access to more money...it is not going to stop bribery(in fact you could argue it will increase i.e. "If you come here we can pay you more money than if you go..."), being "guided" towards shoe companies, agents and so on.