It's much more difficult to compromise someone's computer than it is to obtain/get one of their passwords thru phishing/guessing and then try the combination on

It's much more difficult to compromise someone's computer than it is to obtain/get one of their passwords thru phishing/guessing and then try the combination on a bunch of sites. It's -vastly- better for casual users to have secure, single-use passwords instead of what most casual people do: have 1-2 insecure passwords with variations. Thus allowing any phisher to get access to everything anyways. Just because something isn't perfect doesn't mean it is not an improvement.