Re: People can reform
That's a large part of it, but trying to figure out who should appoint/elect the Commissioner instead strikes me as a can of worms; hence my proposal to give responsibility for business affairs to a President appointed by the owners and serving at their pleasure; while keeping the Commissioner (elected for a renewable, fixed term) responsible for discipline. In the latter case, the term should be long enough to allow the Commissioner to take the long view and to focus on the integrity and well being of the game itself without having to worry about short term fallout; and to make it unlikely that he would be removed for making a single unpopular decision (as it is likely Fay Vincent was for banning Pete Rose).
I'll note that when the office of Commissioner of Baseball was created and for a long time afterwards, the Commissioner was focused mainly on discipline and the integrity of the game, while the league presidents remained responsible for day to day business affairs, scheduling of games, hiring and firing of umpires, etc. One of the reasons why this structure worked was that in the wake of the Black Sox Scandal, the owners didn't want to be held responsible for cleaning up the game, so they delegated the job, and the first Commissioner was strong enough that the owners were afraid to remove him; and once Kennesaw Mountain Landis was dead, the division of responsibility was well established and the job of Commissioner was deemed indispensible. In the end, the division of responsibility failed because the owners wanted more of a focus on money and marketing at the top, so they fired the Commissioner and appointed one of their own (Bud Selig) in his place, then replaced the traditional federal structure with the existing unitary one (naturally, I think both were severe errors).
In the case of the NFL, Pete Rozelle was so good at popularizing the game that marketing became the primary focus of his successors. To his credit, Rozelle knew how to properly balance the business and the disciplinary sides of the job, which is why combining them worked until he retired; but it hasn't worked all that well since. I don't know what the story is in the NBA, but I suspect it is much the same.