Originally Posted by
NaVi
I have always believed that the body represents the powers of the hero, that's why for me.
Thor (Marvel) is fast but his main power is strength, that's why he is a bodybuilder.
Flash is a sprinter, that's why he's tall and slim.
WW is strong and fast alike (warrior), so she has a perfect physique.
Superman is something similar to WW, but his strength is seen as his main power, so without becoming a bodybuilder he has to be big, Cavill in MoS but taller.
As for his muscular definition, I don't know if it's a comic or a fanfic, but I remember reading that Kryptonian evolution makes his body develop more effectively, if you add his powers to that, superman has an almost perfect physical development .