I guess it makes perfect sense if you live in your own little bubble of what morals should be. If you don’t lie, cheat or steal and try to do right by other people but wear revealing clothes you’re a morally upright person by *my* standards. My younger DD’s group has mashed every bad, grungy fashion statement every conceived into some kind of franken style. Piercings, colored hair (usually un brushed), weird accessories. They also eschew gender norms and labels. As a group I’m sure they raise eyebrows but they are all damn good kids. First to jump into action if someone needs help and bringing “outcasts” into the fold. I’d argue anyone who judges them without knowing them are the ones who need to check their morals.
The thing about generalizations- they are done because nobody can know every single person of a group consisting of millions of people. What they can do is notice a change in how that group is compared to how the group they belong to is. Of course not every single person belonging to it is the exact same way, but enough of them are that the change is noticeable. There's even a whole field of study about it.

And yes, morals are subjective, people have different scales for what they think is morally right or wrong.
Personally I think people get way too offended and uptight about what other people think of them, or their kids generation. I really don't care, I know we (me and my kids) are all good people and that is all that matters. I also know there are plenty in each of our groups that do fit the generalizations and stereotypes of them.
Besides I also know that one day my kids will be the older generation clutching their pearls about the youngest one. And that younger generation will complain that they are being unfairly judged. This is nothing new and it isn't going to change. I choose to accept that and not let it get me bothered. YMMV.