Yeah, he's his own man, and his gimmick isn't being superpowered. And I think that is something that people can relate to. Go back to when he first showed up in the Winter Soldier movie and Cap is running laps around him. Clearly the audience is meant to relate to him in a comedic way there. He has skill, but also heart and will, and that does make him a great character. So, that seems reasonable to me that he wouldn't want to juice. Beyond that, we saw what happened when they attempted to replicate the serum before with Abomination, and I'm not sure I would be thrilled to sign up as a guinea pig for another try.
