You honestly believe that arrogance is a barrier to being F1 champion?
It might not be a desirable character trait, but would you say Michael Schumacher, Ayrton Senna, Alain Prost, etc, etc weren't arrogant?
Anyway, I'm pretty sure that Button said no such thing. He might have said that it was turning out the BAR were being Ferrari's main competitor, which is true.
The main theory for why BAR have suddenly taken off is that they've got rid of JV's arrogance and are able to perform as a team now, instead of Jacques and his backing group.