Which, to cut back to the OP, is why this whole issue isn't really an issue at all. The OP had a problem with children of the future not having 'evolved sensibilities', but again that's because children are always in a process of learning. Just 'cause Dad is a morally adjusted Captain in Starfleet with high principles and a sense of platonic ideals doesn't mean his 8 year old son is.
Here's the thing though... those kids (in Trek) SHOULD have different behavioral patterns already by that point in their development.
Children may be in the process of learning, but again, if you are born in an environment where factors do not exist that contribute to one child bullying others, chances are the kids who grow up in such an environment will have NO REASON to bully other kids.
What we saw in 2009 with Vulcans bullying and hitting Spock seemed nonsensical to me.
The writers intentionally wrote things this way to create 'drama'.
Vulcan was already part of the Federation at that point in history for nearly 100 years... how is it possible that Vulcan educational system was so badly set up to discriminate against vulcan/human hybrids in an organisation that emphasizes principles and ideals such as liberty and equality?
Especially when these kids are already learning advanced things at a very young age?
The principles and ideals of UFP would be something these kids would know by this point in their lives.
Sure, some Vulcans had a negative outlook of humans in the 22nd century... but you can't tell me those aspects would have prevailed for nearly 100 years (despite the fact that in reality, some views persisted for longer - which is clear indicator of lack of exposure to relevant general education, cirtical thinking and problem solving, and living in a socio-economic system that generates conditions where outdated views are ALLOWED to fester and persist - aka, the root problem is NOT addressed, only the symptoms are).
The type of society and environment UFP promotes would have negated those behaviors by the 23rd century when it comes to adolescents... especially if the union is supposed to be as progressive as claimed and DEPENDS on these species sharing information, knowledge, technology and science freely and openly.
There is obviously a disconnect between how the UFP is described constantly, vs how some writers keep injecting elements that don't fit the narrative into it to make things 'dramatic'.
I'm not saying that there wouldn't be 'problems'... but nothing that would result in kids bullying, hitting on each other, etc.
Not you, but the OP seems to suggest that by the time Star trek's 24th Century rolls around then kids won't have tantrums, or ever say anything hurtful without realising it, or hit each other, or themselves decide to become bullies... and that's... well, it's nonsense.
Its not nonsense because tantrums, or kids hitting each other or becoming bullies (again) doesn't 'just happen'. These are responses that arise from environmental stimulus.
If you change the environment in which the kids live, such behaviors will not emerge.
Humans may be born with tendencies for certain things, but whether or not those tendencies emerge or not depends on the environment in which we live.
Trek kids in UFP are supposed to be growing up in an environment where the conditions which give rise to tantrums, bullying and kids hitting on each other DO NOT EXIST (or at least shouldn't exist and are minimized).
If they do, then the writers keep saying they created a supposedly radically different socio-economic environmet one in which (apparently) kids STILL ('magically') behave like they do now (suggesting that kids hitting, bullying each other or throwing tantrums is somehow an 'inescapable fact of life').
I'm sorry, but THAT is nonsense. And THAT's exactly the same kind of issue I have with Trek as well.
If the writers were going to say UFP (or heck, just Humanity) created a fundamentally different system, then they should stop injecting real life patterns of behavior just because they think those are 'the norm' or something that will happen regardless (because that is the kind of message they are sending - they are propagating nonsense).
They actually had a chance to move away from showcasing nonsense that happens in everyday life and portray a different kind of future.
One other thing, kids throw temper tantrums as a way to express FRUSTRATION. Again, a clear response to environment.
For older children to throw temper tantrums, its likely learned behavior.
Parents tend to raise kids without knowing what they're doing. Without understanding the basic science of human behavior and living in an existing system, they 'reward' some types of behavior while 'punishing' others.
Its a rather primitive way to behave towards kids if you ask me... and humanity as a whole (and Trek) needs to be REVAMPED to better understand the science behind human behavior and how environment impacts us.
'Kids are going to be Kids' isn't necessarily an indictment of children I should add. There are certain things that children do which are pretty common amongst kids in any culture. Kids like to explore, they like to play and learn, but also, unfortunately, (some) kids do like to kick other kids around. I'm no expert but possibly that's just instinctual alpha pattern behaviour? In any social group, someone is always going to try to rise to the top and domineer others I guess?
Again, you are suggesting that kids kicking other kids is 'just natural' or somehow part of their biology.
This would be a clear indicator that another environmental factor exacerbated aggressive tendencies in the kids that hit other kids and are actively acting out on it because of that.
You mentioned that in any social group, someone is 'always going to try to rise to the top and domineer others I guess'.
You never however said WHY this happens.
Its because we live in a system which is centered around competition (which is learned behavior). The system we created is effectively set up in such a capacity where these is this concept of 'getting ahead' of others. Effectively we are forcing kids to competet against each other which causes these problems in the first place.
Grading is another form of competition. Teachers and parents 'favour' better grades, and encourage kids to 'compete' against each other to get ahead in class.
This is very clear to anyone who closely starts examining how the system we live in works. Trouble is, most people don't.
You mentioned Vulcan kids, but as you said, behaviour doesn't arise in a vacuum. Those same children weren't born logical. Following the teachings of Surak is learned behaviour and those children are still learning and in some cases possibly rebelling against the idea of being logical.
I can imagine those Vulcan bullies being sweet as pie and highly logical in front of their parents.
Children rebelling (again) is not something that is 'part of life'.
Children rebel because more often than not adults impose limits on the kids without adequately explaining the context behind those limits.
This results in confusion.
Most parents in real life don't have the time (or energy) to explain things to their kids... and a LOT of parents consider kids as being 'incapable of understanding' these things (they are perfectly capable, they just need the proper explanation that they will understand - if the parents or educational system doesn't do this, then they are doing it wrong).
In Trek, the idea is that adults would have A LOT more time to spend with their kids (no money... no worrying about finances, stress that can result from that, etc.)... and there is this premise that such people would be better educated to know whether or not they actually WANT kids in their lives (I wouldn't expect these people to be having kids on a whim).
When I 'rebelled' against a lot of what my parents said, it was because what they said made no sense.
They said one thing, while behaving in a completely different manner.
This is quite common. The type of society humanity lives in shares the same socio-economic system across the globe. It says one thing on paper, whereas in practice it does things the OPPOSITE.
Many adults behave in exactly the same fashion which results in kids being confused with what they are being TOLD vs how people ACT.
Since kids mimick behavior from adults and from their peers, how other people act will inevitably influence a child's behavior.
You're still seem to be trying to say that some behaviors in kids (like hitting on other kids) 'just happen'... when in fact we know it doesn't.
There are always reasons for why kids attack others or why they behave as they do... most people just ignore the environmental factors (aka, the system itself and adjacent factors) and then do nothing to change the conditions which resulted in this behavior (resulting in addressing the symptoms and not the underlying cause).
Aggression can be directly learned through operant conditioning, involving positive and negative reinforcement and punishment. Bandura proposed that aggression can also be learnt by the indirect mechanism of observational learning. Social learning theory maintains that children learn through a process of imitation.