Yeah, I'm surprised by this, too.Why is this blowing up like this? Why not everything that came before?
I thought it would be another scandal, but a bigger one. But this looks like the last straw for many.
edit:
Yeah, that's it.Sam Wang from the PEC would argue that a lot of Republicans are dumping Trump not because of what he said, but because it was a way to ditch an obviously loosing ticket.
He put it better than I could:
http://election.princeton.edu/2016/10/08/what-color-is-the-swan/#more-17785