3. Supporting Characters Who Actually Matter
One thing that really bothered me about Iron Man 3 in particular was that the supporting characters were woefully underdeveloped and just didn't matter all that much; take Stephanie Szostak's Extremis soldier. Fans speculated for months beforehand that she was actually going to be playing Wasp, though this of course turned out to be disappointing bunk. It would have been a great way to expand the MCU even further, but instead she's just a generic soldier, and given her decent physical resemblance to the comic book version of Wasp, it just feels like a wasted opportunity. I'm not suggesting for a second that filmmakers should shoehorn in comic book characters both major and minor just because they can, but that sometimes it makes sense, and yet writers don't seem to consider this. While not everything needs to be trying to appease the comic book fans, sometimes it doesn't hurt. And on that note...