If they got rid of the brand split, then I think having four championships will be the perfect balance: WWE Title, IC Title, Tag Team Titles and Women's Title. That way, you have a title for main eventers to fight over, a title for midcarders/upper midcarders to fight over, a title for tag teams to fight over and a title for women to fight over. Although I personally hate women's wrestling, so I would try to replace it with bringing the Cruiserweight title back or something, I dunno.
As it is, I don't know if getting rid of the US Title is the answer. They just need to feature it more and actually start putting their US Champion on television. The fact that Raw is a supershow every week sort of damages it as well, because it makes one of the world championships kinda look like the second most important title, thus making the IC Title look third most important, thus leaving the US Title in 4th place at best.