The problem is that there is no character-type pattern - most especially not your base16 suggestion - that will satisfy every site. Many sites require special c

The problem is that there is no character-type pattern - most especially not your base16 suggestion - that will satisfy every site. Many sites require special characters. Others forbid them. It's literally impossible to satisfy both with a single non-parameterized generator, and as soon as you start adding parameters those effectively become hidden parts of the domain name. Worse, many sites don't even tell you what the requirements are on normal entry (only on change). If you can't remember what particular tweaks were necessary then it's back to the good old "forgot my password" dance - making your email password your effective password for all such sites. It's easy for app developers to be careless or "clever" about their password rules, but it's a pain for users and it's bad for security.