[andrepd]

I don't think that's such a big problem for most users. The vast majority of websites impose only a few easily satisfiable constraints, at most: small and capital letters, numbers, symbols. This covers 99% of websites, and the default generator can cover this by default by generating something like bhAwG9$nj#.

For those corner cases you can have different password generators, for more complex constraints. But overall it's not a big hurdle.