Ugly solution that didn't expose a UI for sites that didn't support it and still had plain username/password forms. So it's completely impossible to bootstrap this by making some of the features useful to browser users before it was widespread.

Needed a js library because it worked at the wrong level of abstraction and put browserid.org in the middle of the transaction for no sensible reason (well no sensible technical reason but a perfectly sensible political one).

This was not developed by someone thinking "how can we solve a problem our users have" but by someone thinking "it would be advantageous to be in the middle of login transactions and there is a user problem we could bolt that functionality on to".