What I never understood is why Google's motto wasn't "Be Good". Logically and linguistically, "be good" is simpler than "Don't Be Evil", even if they aren't logically equivalent. And, as any psychologist will tell you, you don't say or think what you are trying to avoid; instead, you focus on something else that achieves the same goal, so if you were trying not to be evil, the word evil shouldn't even be in the motto.

If they had focused on "Be Good", perhaps they would have fully instituted good service from the beginning and embraced personal customer contact.

Because "Be Good" can be ambiguous, e.g. it's also equivalent to "Don't Be Bad [at doing something]".

Probably because it's easier to agree on what is evil, than what is good.

Isn't there anything between good and evil?

Chaotic neutral?