If the idea were to minimize the number of written accidentals, the signature without flatted B would often be preferable. If the convention would allow that, it would still not be any more "correct" though, and even less "logical" in a sense. The notation system is largely determined by its history - like it or not.

Many alternate systems have been invented, less space-consuming, easier to learn, more suitable for equal temperament, more suitable for pure intonation, more symmetric for all keys, easier to read by humans, easier to read by software ...

We are still typing on computer keybords layouted as if for mechanical typewriters.