Switching one uppercase letter in an otherwise lowercase password adds exactly 1 bit of entropy (per switched letter). On the other hand, any extra lowercase l

Switching one uppercase letter in an otherwise lowercase password adds exactly 1 bit of entropy (per switched letter). On the other hand, any extra lowercase letter will increase the entropy by 4.7 bits (assuming a password on [a-z]). Given that most passwords have at best 2 uppercase letters, I would argue it is safer to force longer passwords than passwords with at least one uppercase letter.