Cultures can also be very weird about how they treat schoolchildren. The kids weren't responsible for any part of the Holocaust, and they're theoretically apologizing to someone who can't hear it.

I can see some point in all this if you believe that Germans are especially apt to genocide (I have no strong opinion about this) and need to keep being reminded not to do it. Still, if this sort of apology is of any use, I'd take it more seriously if it were done spontaneously by individuals.