I have very complex, mixed feelings on this issue. I do believe that at school children should be dressed "appropriately". Of course, the problem, is what do we define as "appropriate" and I'm fully aware that what I consider appropriate is NOT what someone else would consider appropriate.
In my perfect world, skirts as school uniform would be completely removed. I know that 90% of the world disagrees with me on this and I understand that, but my thinking is that the only issue with short skirts is that they are less practical - already at primary school DD tells me that she doesn't always like sitting on the floor (considered a perfectly normal thing) because her knickers show. I have spoken to other parents who tell me that their girls don't like running around at playtime as if they accidentally show their knickers, they get teased. But societal expectations, even at this age, mean that even at our primary school where girls can wear shorts/trousers... almost none do. I have begged and pleaded with DD... to no success.
This problem is x100 at high school with short skirts. I don't care about short skirts. I DO care about children at school wearing clothes that in any way restrict them from doing anything and everything they want to do.
Hence my "cancel skirts/dresses" for school uniform mantra.
Overall, re make up etc, I remain uncertain. I personally hate heavy complex mae up on young girls but this is the world we live in. I don't want make up that again, becomes a distraction at school - eg meltdowns because they've lost an eye lash or teasing or more time spent redoing make up than learning. But I don't really see how a bit of make up, or an ear ring on a boy, or whatever is really a problem.