As somebody who was never a fan of the Ultimate Universe I’ve noticed that it was about the time when those titles stopped being published that the main universe started to go down the tube. What I think is that the Ultimate Universe gave creators a place to do their own versions of classic characters and go as crazy as they want with no responsibility to maintain continuity and core aspects that were put into place decades before from iconic creators. When the Ultimate Universe titles started to resemble the originals so little, they all just disappeared via cancellation. Then with no place to experiment like that, people brought that mentality to the main titles. No longer was it excusable to keep a classic costume because the version in the Ultimate Universe had the same costume used in the movies. They had to change the characters in the mainstream universe now and no longer have a place where they can do their own versions that can deviate away from the original characters.