Further pollute? Not sure that it can get more polluted. All of the stuff you described is already happening. There's a very healthy black market for autographs and merchandise. Letting players benefit from their own likeness wouldn't do anything that isn't already being done.
I think it would be easier to exploit. Now you wouldn't question if a high profile player has a really nice car because he'd have a valid stream of income from his likeness. Boosters could then "legally" pay him $500 for his autograph. And you know the rich would only get richer with more opportunities to pay athletes.