The functionality is part of every decent password manager, which takes care of basically all your passwords, not the ones stored in your browser. So I don't understand the enthusiasm.
these are the reasons a browser built-in password manager is ideal for many people:
1. most people don't need many passwords outside of the browser.
2. in-browser password managers can offer a better user-experience than standalone password managers. (although, so far, firefox's built-in password manager is lagging behind in this regard.)
3. password managers integrated into the core of the browser have a smaller attack surface than those implemented as plugins.
4. users of a particular browser already trust the browser vendor with their passwords, at least enough to let the browser see and transmit them every time the user logs in to a site.
