The problem with a super heavyweight division is there will be no one to fight in it. It would be mostly fat cans who were too lazy to cut to heavyweight. They'd have Brock, Shane, some 600 lb punching bag sumo guy, Butterbean, and Bob Sapp as the big names. Honestly the weight classes in effect are enough if not too many in my opinion. Need diversity and more big name headliners? Start actual tournaments where the fighters have to fight more than every six months and fight multiple opponents in a given night.
The multiple classes did hurt boxing, but not as much as shady promoters and the fighters they hype up taking half year vacations between absurd pay checks. Start an open weight tournament under modified rules and let all these guys trying to play belt swap and saying they're the best prove it. Heck, have it in Japan if they won't sanction it here in the states. That'll help re-globalize the UFC and force more talent to either evolve or fall to the wayside.