Kids should absolutely be taught love, compassion, and tolerance, (and I commend any parent who focuses on that), but they should also understand the reality of life. People will hurt them and many of them will do it on purpose, just because they are bad people. No other reason.
A "bad person" is just a person who disregards free will and consent. And it is a person who is willing to initiate force to get what they want.
We should teach kids how to discern early on which people to avoid and which to trust. :)