Depends on where you are in the world. Java is required for online banking in Norway, while it's mostly unused in Sweden, the neighbouring country. Both use Java for online verification to government sites.
(And if this really is just a click-to-play type inconvenience, well, that's a hell of a lot less than the hoops that users are used to going through in order to get into their BankID banks here.)
Exhibit A: healthcare.gov
Do they? I thought Sweden used the online bank identity system for verification (bankid), which is either a standalone downloadable application, a smartcard image, or an mobile app. Not sure how an Firefox policy would effect this even if some parts of the bankid uses Java.