I'm guessing from your reply that you don't think its important to emphasise kindness as part of supporting your childrens' growth. If that is the case, what do you emphasise if anything?
Kindness has a merit on it's own and ultimately it's a good idea for a person to decide what they want to be and take responsibility for their choices.
Being kind "because there are too many unkind people out there" sounds wrong. I have no idea how they measured the "too many unkind people out there" but lets assume for a moment this balance shifts - then what? They should be unkind because there are too many kind people out there? Is this is a simple act of balancing the two sides?
They could have said:
"Most people are kind. Be kind and most people will be kind back." Or something with positive intent. Instead they seem to be priming a superiority trip.
Or they could said:
"Be kind because it's the right thing to do."
This sounds wrong because you feel we need more assholes out there, or you feel we have the proper amount?