Definitely agreeing. As fantastic as Rourke is an actor (I practically cheered and cried whilst watching the Wrestler recently), Whiplash as a villain needs a far better look than half-nekkid with some power lines attached to him.
That said, a lot of noise has been made over Rourke's willingness to research the role and go and find out about Russian prisons and whatever, and the sort of tattoos they get inked, and as such, that just might be his costume. Still, he is meant to have some sort of association with Rockwell's Justin Hammer, so who knows? Maybe he can suit up Whiplash properly.
I still think Rourke would've made a better Crimson Dynamo, but then that might be too similar to the Iron Monger for comfort.