As far as I know, it's only ever been Steve who could pick it up, besides Thor.

Oh, really? I didn't even know that. Is that a comics thing or an Avengers thing that I completely missed?

I can see Erik trying so hard to do it that he's bending literally every piece of metal around him, and the Mjolnir's just like, 'lol, no'.

Mjolnir would probably add insult to injury by having Erik accidentally faceplant himself trying to pull the hammer toward him.