If you mean an extra password, the answer is that most people don't want to type in a password when they open their browser. Think it through and try to see the issue.

I don't see your "issue", as using a master password does not "defeat the whole purpose of password saving" at all. Many people have different login credentials for different websites (not only passwords, also login name or email) which are hard to remember which one you used where. Having access to them with a single master password is convenience.

I like the way this is handled in Opera, where your passwords can never be accessed/viewed in plain text at any time. Once your login data are stored, you can simply use them via CTRL+ENTER on the login form and the data is pasted into it. If you want to you can use a master password to restrict access to that data. And you can even set a time after which the the browser will forget that password and then asks for it again after e.g. 15 minutes.