My own personal view is this: There is a stronger movement to Open Carry because of the pressure from the other side to outlaw guns. People, and perhaps Americans in particular, have a tendency to push back against anything that limits them. So it's only natural that the Open Carry movement has ramped up.
I'm not a fan of open carry because I happen to think that the notion of universal concealed carry has a powerful effect on stultifying criminal behavior. Fear of the unknown is a powerful emotion.