5 Inherent Problems That Explain Why Every Marvel Villain Is Boring
5. They're Usually Made Up Of Several Different Characters

The MCU version of The Mandarin wasn't The Mandarin; Iron Man 3 pulled the rug from under us all, audiences laughed and fans were annoyed. But, getting past the furore surrounding the film's release, that was really just the latest in a long line of Marvel chopping and changing their villains.
Micky Rourke's antagonist for Iron Man 2 was a mixture of Crimson Dynamo and Whiplash, with the backstory of the former and the name of the latter (the changes in the costume even reflected that). In the comics Darren Cross was a mutated human killed almost as soon as he was introduced (only to be resurrected recently to tie into the film's release), while Yellowjacket was (at least at first), Hank Pym at one of his darker points, yet they were mashed together for this year's Ant-Man.
Most of the other villains are dilutions or major variations of their print counterparts. This is to be expected somewhat when adapting decades of comic continuity into a two hour film, but it's consistently to the point where they're not anything close to the character they were intended to be, and thus become little more than anthropomorphic deux ex machina.