#1 Mr. McMahon's unwillingness to listen to anyone else

A big thing that would need to be done to help fix some problems is have Mr. McMahon acknowledge that he is a part of the problem. That would never happen, however, as he is a senior citizen and set in his ways. Instead, the blame is likely put on the writers and everyone but himself.
Realizing that some of the problems your company is facing are your responsibility isn't something that billionaires do. So until he takes some of the blame, they will likely continue to suffer through the same problems they've dealt with over the last few years.
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He probably isn't considering anyone else's ideas because he always has the last say on things. This has routinely led to the scripts for shows being re-written even hours before the shows air. The most recent episode of Raw reportedly started without a finished script. What's so wrong with the original scripts that they have to constantly be changed on the day of the show?
Another thing that McMahon apparently doesn't do is watch NXT. How is that possible? Don't you want to see who has potential regarding some of the up and coming stars? That's likely the reason why so many Superstars suffer name changes or gimmick tweaks once they transition from NXT to WWE proper.
Mr. McMahon is a visionary who brought WWF/WWE to the forefront but a lot of things have changed since he did that. Without acknowledging that other ideas can work, it has kept WWE is the same holding pattern that led to the ratings' issues that they currently face. They need to adapt and evolve or be doomed to repeat history.