I don't think it's good to rely on the licence to carry this sort of information. Even if I have a library that I intend to maintain as polished and continually updated code, I'm going to have a licence disclaiming a legally-enforcible warranty.

And I might have a library that over the years changes from being shitty to high quality (and back!). I wouldn't want to go changing the licence to follow its lifecycle.

I think it would be valuable to have some widely understood conventions of text you can put in the README to set appropriate expectations.