It wouldn't be on by default, but a setting (or add-on) that will allow the user to have all passwords displayed as I put them in instead of scrambled and not have to toggle each password.
As complex as passwords are these days, it's hard to be sure you've got them right unless you can see them, and I am alone with a desktop. Having to toggle each one on, when it's impossible for anyone to be looking over my shoulder, is annoying. And I don't want to use a primary password.
I should be able to make this choice. I'd like to have it in both Firefox and Thunderbird.