It's worth keeping in mind that fighters like WW, and Batman are supposed to be able to fight and move. If you get real big and bulky you can barely even move, so if the characters are going to doing a lot of running and moving when they fight then they can't be to big.
That's not an across the board fact. Captain America's Chris Evans is very built and is quite flexible / fast, and performs believable stunts.
I find some (not meaning you) fighting against the very muscular superhero (which has more than 60 years in the comic source) coming from some revisionist desire to make those who are
supposed to be larger than life in every sense watered down to weak, average people in appearance. They seem to resent muscular characters. That was one of the motivations behind casting Michael Keaton as Bruce Wayne/Batman, and it was a farce, as that short, thinning-haired, weak-faced, non-muscular man was the complete opposite of every illustrated version of the character up to that point in history.
Of course, Tim Burton (in one of his 1989 interviews promoting his Batman film) was critical of (in his words) the "square-jawed hero," so he--with his obsession with odd and/or misfit characters--tried to turn Batman into something he was never meant to be.
Comic characters are not the cast of
Big Bang Theory. They are more than the man on the street, which was part of their appeal from the dawn of superhero comic characters. Removing that defining visual screams of some rather warped social engineering at work, rather than trying to make the fantastic elements of the comic come alive in an adaptation.
