It would've helped show the tension between the two and set up Civil War. Ultron was horrible, and Hulk should have been portrayed better. The Hulk/Black Widow romance was bad, like where did it come from? I don't think Marvel's burning out, though. Age of Ultron still made over 1 billion dollars, and it's in the top 10 highest grossing movies. AoU's problem was that it didn't live up to the first film and that Joss Whedon had to cut out scenes that probably would have helped the film flow better and make more sense.