The "Growing up" reminded me of this song: https://www.youtube.com/watch?v=5ja-mHeYAKM
IMHO, it doesn’t make sense to blame “society” for being pre schoolers, any more than it makes sense to blame individual humans for becoming mentally ill. Both are just failure modes of our mental hardware (our tribal-status instincts in the societal case.) The only solution to either that would “stick”—what I would interpret “growing up” to mean—is to remake ourselves without those failure modes.
Anything less might help individual humans who get some sort of maintenance treatment for their failure modes; but our society as a whole will still be a function of interactions between both people who have treated those failure modes in themselves, and those who have not yet (because e.g. they aren’t aware yet that they have a problem; or don’t see it as a problem; etc.)
Mind that when I mentioned society as a whole, this is inclusive to its individual parts: There is no society without individuals and as such any judgment on a society is a judgement on its parts. That being said, I know it is a naive view, as no one can condemn a society completely.
As for the bio engineering to try and weed out the "bad wiring", I am not even sure we are close to identify them clearly, as seems to indicate the science articles about the brain and other nervous system in recent years.