You cannot hash passwords in a password manager. It has to be reversibly encrypted and turned back into plain text before utilisation.

So when people complain about password managers storing plain text (as opposed to hashing) they're barking up the wrong tree, it is a necessary evil.

You just want to see them encrypt those plain text passwords so that offline recovery is harder. That's what both Firefox's master password, CryptProtectData() for Chrome/IE, and the key-chain in OS X provide.