Button damaged his own car. That is what that driving style does.. 
Anyhoo.. Only the foot part of the end-plate was damaged - not that significant. Rosberg lost a much bigger chunk of his end-plate and he was fine. Button just couldn't excape from the Red Bull; notice he said nothing much of the wing after the race.
On the BBC Forum he did mention it and said he thought he was doing a good job of managing the problem before Vettel took him out. Hamilton was definitely faster all weekend but he wasn't
that much faster, the damaged front wing definitely had a large effect on his pace.
As for Rosberg, I don't remember him driving around with a broken end-plate but, even if he was, we can't really know how extensive the damage to either car was and what effect that would have on their pace.