I'm a lolita who is often in a similar situation, though I try not to complain about it since it's my choice to wear less eye-catching gothic coords and I'm currently too poor to do anything about my ugly face and short, stumpy body. It just feels bad to be the less pretty or eye-catching one and to know that you'll never be as cute without a lot more effort. Maybe in cosplay that's not true though, since you can make a better quality costume or show some thigh or tit, idk.
Anyway, when the seemingly entitled girls complain what they're actually doing is expressing their emotional distress in a way that might hurt their cute friend's feelings and hides their vulnerability. They're probably not doing it consciously, but it's much harder to self-reflect and try to improve than to just blame other people.
Like, imagine saying,
>Man, I feel kinda bad when no one takes pics of me. Friends, how can I improve my look for next time?
That can be hard. Even if you are a self-aware person you have to learn to take feedback before you can say something like that. And it gets harder when your friends assume you're fishing or need support and inevitably go,
>Nooo, you look great! I'll take pics for you, come on
And you have to double down like
>No, really, I mean it. I want to improve.
If you don't have the emotional maturity to deal with that or don't realise that these feelings are on you, then blaming someone else is the easiest way to protect yourself from criticism. Everyone, male or female, does it at some point, and that's basically what's going on with these entitled girls too.