Is the public key protected by PIN or confirmation preventing rogue websites from stealing it? Having your public key leaked would link all your transactions for the life of the seed.
This is actually a good point in the context of Trezor Bridge. It's not an issue with the extension because you have to manually allow it to run on every website that tries to use it. With Bridge though, it's a tiny web server that is potentially always running on your computer, allowing anyone to connect. Perhaps Trezor Bridge should require the PIN to be entered before a new connection can be made?