Making others feel good adds joy and quality to [kids'] lives, and it contributes to the good of the whole. Of course, those nice kids might get hurt sometimes, because others won't reciprocate the kindness, but that's OK. There are more successes then failures in that regard. And it sets a pattern for the children that will give their lives a lot more meaning down the road.
This goes hand-in-hand with teamwork, the ability to relate to people from all walks of life. People become who they are through a variety of factors—upbringing, education, socio-economic status, early experiences with other children, and so on. If I can teach my granddaughters to understand where people are coming from and to try to interact with them regardless of how different they may seem, I will consider myself a successful grandfather! And my granddaughters will find that what they give comes back to them, in friendships, in their careers, in how they will raise their own kids.
Now, I'm not naïve. We always want to protect our children and grandchildren, not send them out to hug every stranger who walks by. And, yes, there are times when we'll tell them to avoid certain people or types of people. But we can still equip them with a sense of the world and an appreciation for the circumstances that make others different from them.
We might think that world's never been more daunting or dangerous. And maybe that's true. But, remember, that's exactly what our parents and grandparents thought when we were kids.
So we can and should teach our grandchildren how to recognize and avoid danger, but I think that's secondary to teaching them how to love and play nice with others. And we do that by loving them and playing with them—every minute we can.