I think Joe Weider made a mistake when he created a contest that guys could win year after year. In 1965 Joe and Ben came up with this idea because they were competing with the NABBA Mr Universe in England. Today there is no competition for the top contest.
In 1941 the AAU had to change the rules in the Mr America contest because it looked like John Grimek, who also won in 1940, would be winning every year. That was a good decision and we had a new champion every year and it gave everyone a chance to win the top title in America in those days.
I think much of the controversy over the years occurred when guys like Arnold, Lee Haney, Dorian and Ron Coleman won because of their reputations and not necessarily their condition in some years. We have seen how it has been a bit difficult to dethrone a current champion.
There could still be some Grand Prix shows where past champions can compete but the Olympia should be for non Mr Olympias. I would predict that the excitement and interest would improve, too.