'Why do schools not try and teach the very clear and easy-to-understand morality of logic, personal and societal responsibility and realising what is good and bad for one's self (that Atheism espouses)? Such teaching would also feel very empowering and 'grown up' to children.'
Yes, it's called Citizenship, and it does not work. I have taught citizenship to years 7,8 and 9, and done the 'if you have rights you have responsibilities bit', and they could not give a toss. Understanding of societal responsibility comes with age and maturity and that is exactly what children do not possess. They are for the most part egocentric, and cannot see beyond their own desires, or grasp the bigger picture. They have the idea of their rights on a personal level, but do not feel that they need be burdened with the responsibilities that come with those rights.
I have yet to see that logic has any morality - it is logical to kill off everyone the day before they draw their pensions, so reducing the burden on the health care system, and government finances, and freeing up large family homes for those who need them, but I don't see us a society doing that quite yet.
As for the atheist stance being taught; that is where I started most of my lessons from, and I always acknowledged that lots of my students would not have a religious belief.
SGB - I think it was Herod who ordered the massacre of the babies and last time I looked at the NT, he was Jewish, not Christian.