Half the appeal of online banking using a web browser is that I can access it from any machine I choose, wherever I happen to be. If banks start to make physical devices mandatory for access, that convenience evaporates in a moment.
Two-factor authentication is fine and dandy, but to be workable it needs to be a) portable, and b) require some common token for multiple services. If I have to start carrying separate tokens around for my job, my bank account and anything else using a similar mechanism, my pockets are going to bulge in no time.
Maybe the answer is a man-bag...