For instance, if boxing fell under a UFC-type organization, we would have seen Mayweather-Pacquiao years ago. Now we probably never will (or if we do, it'll be at a point when we don't give a shit anymore).
True, they still pick and choose "interesting" fights instead of the legit best fighters.. but the end result is that we get "interesting" fights. In boxing, promoters choose fights based on how likely their boxer is to win. A young boxer that gets a loss in his first 10-15 fights is pretty much done for his career, so they play that game way too much until they get to the point they can contend for a title.
When's the last time you saw a non-championship fight that could legitimately go either way in boxing? When was the last time you saw a non-championship fight that you actually gave a shit about? It rarely, if ever, happens.