This thread is interesting and it is good to talk about beauty in-depth. I don't actually think it's wrong to take an interest in appearance or to compliment someone on their looks or style, and I think it is definitely not just a female thing.
Something has gone wrong somewhere when it comes to people, mainly women, obsessing over it and undergoing traumatic and unnecessary cosmetic surgery and hating parts of their body and so on. But all of this is on a sliding scale.
There is an extreme and worrying end of the scale, and there is normal, healthy self-care and titivation which applies to everyone and is what saves us all from being flea-ridden unwashed cavepersons. After all if someone comes into work having not washed or taken care with their clothes or grooming at all, you would start to worry - that they might be depressed, unwell or had some kind of problem. We do all use our appearance as a signal and notice each other's appearance.
If I say to DD you have such nice eyes or to DS I love that outfit you've put together, I mean it, and I am saying I appreciate you in x, y or z way, just as I might compliment a good homework effort, act of kindness or nice drawing. I think it's possible to do that without giving the message "you are more stunningly beautiful than other children and that is what you are all about". I am amazed at how my DC are much more good looking than me IMO, however I don't go on about that to them.
Also, stylishness is a natural attribute that is lovely to see in a person. It doesn't mean someone less stylish is less valuable, but for some people it's their thing. It's a design and aesthetic thing and we don't sniff at those in other areas of life. There's a girl in DS's class who just has it - she's not model-beautiful, she's stylish and I've complimented her a few times on a dress or hairdo. Why not? I can see that when I do, she knows where I'm coming from. Someone noticed the look she took care over. I think that is OK.