They may not be holding meetings to discuss what needs to be done, and they may not be making payments themselves, so that they cover their own tracks, but you better believe that all successful recruiters have at least one coach on staff that makes sure the prime targets are known by the boosters and are taken care of discretely, even if they don't "know" about it.
I honestly think Croom was clean in his early years of recruiting. He really thought he could come in and sell MSU and win by getting players that wanted to be at MSU for the education and the chance to play SEC football. That was evident by some of his early classes. His recruiting picked up when he conceded and decided to play the game. I still think Croom washed his hands of it and didn't directly deal with it himself, but he made sure he had people in place to deal with that side of the game, and your recruiting picked up.
I agree that the NCAA could do more to curb it from happening, especially for the blatant cheaters.
Doing something like suspending a coach for a certain period of time for being directly involved would help some, but I think ultimately handing down some death penalties would do a whole lot more.
The ultimate issue you have with college athletics is that the players can only receive a scholarship and occasional stipends for playing a game that makes loads of money for the university. Often, many of the best players come from families that don't have a whole lot. Some of them have next to nothing. On the other side of things, you have wealthy boosters with loads and loads of cash. The opportunity and the discrepency between the haves (boosters) and the have nots (athletes in many cases) creates an environment where things are going to happen at least on a small scale. That environment isn't going to change ever.
If you allowed all players to receive a salary, even if it was equal across all D-1 universities, along with their scholarship, and you cracked down really hard on the universities caught cheating, you might have a chance to curb cheating somewhat.