Since a lot of sites have unique requirements, but those unique requirements are usually a subset of 1 number, 1 special character, 1 uppercase character, why n

Since a lot of sites have unique requirements, but those unique requirements are usually a subset of 1 number, 1 special character, 1 uppercase character, why not just force the generator to always contain uppercase, always put in a number and always put in a `.` (or whatever the most accepted special character is)? Yes, it ever so slightly reduces the brute force searchspace, but that's non-trivial with a lengthy password.