There are PLENTY of guys in the HOF who aren't perfect. Some cheated on their wives, beat their wives, drank a lot, etc.
On the door to every clubhouse, there is a sign with a list of rules. None of those rules say to be perfect or lead a perfect life, but there most certainly is one that explicitly forbids betting on the game. This is THE sin you can't commit....whether you get over 4,000 hits or just 200.
Why is this such a big deal? If the fans don't think the game is being played on the level or that players' performances have been corrupted by wagers, they won't care. Why should they? At that point, it's ceases to be a game and becomes scripted entertainment with a decided outcome.
That's how fans felt back in 1920 when the Black Sox scandal finally blew up. Fans saw that the game had no integrity and it became a crisis for the owners. They stood to lose a LOT of money. How did they solve it? They had to do something fast to show the public that baseball had high standards and integrity. The owners went out and created an all-powerful Commissioner. They sacrificed much of their own control over the game to preserve their business. They hired a Federal Judge who was known for his love for the game. In the public's eye, he was honorable, so the fans began to trust again. He promptly banned the Black Sox conspirators.
As much as I don't care for Bud Selig, I have to admire his stand on Rose. Bud might be a moron, but he understands these basic principles.
Banishment from baseball doesn't mean that someone goes into the record books and erases Rose's name from every column. It means that he can't work in baseball. He can't play. Rose isn't being demonized or victimized for the heck of it. He made a horrible decision and the consequences of his actions are well-documented. It happened to Jim Devlin. It happened to the Black Sox. Knowing all that, he bet anyway. Was he so arrogant to think that it would be OK for HIM to do it and get away with it? Lifting his banishment would mean just that. He WOULD get away with it ultimately. He WOULD be esteemed in the hallowed halls at Cooperstown. It would be OK to sell out the game, deny it, never apologize as long as you had an outstanding career.