I'm sure there are different needs for the Primary Password but in the majority of cases I just want to protect them from being seen or edited. I do not want to enter a password in order to "enter/auto-fill my passwords"!
Sure - in some cases it can be fine - if you need to restrict access to also using the sites. But if you need to restrict access that way, why save the password in the first place??
I would by far prefer an OPTION to lock viewing/editing of saved credentials - but still allow them to work as expected for saved sites. The password prompt would be presented if there is an attempt to view or edit the passwords.