Well I could say the same about Civil War tho… both hinted at a larger, richer subtext but both completely fumbled them. To be fair tho, I think a lot of it has more to do with the Disney higher ups who might want more straightforward movies, which was ultimately inevitable because… Disney.
Buuut, within that context, whoever decided AoU’s character directions made some odd choices. The most obvious is of course Black Widow who got relegated to a Hulk sidekick/love interest position, whereas she was so much more in both Avengers and WS. I personally don’t like what they decided to do with Ultron, becuase he ended up being another generic MCU baddie, but that’s mostly a matter of personal opinion.