Galaxy
I think people can do what they like. I think it's fine to challenge some of the sterotypes that are associated with gender reveal parties in the same way we challenge stereotypes about other groups.
This is my take on it.
I don't care what people do about parties - it's absolutely harmless, although I do wish the 'gender' nonsense would stop, and think it would be less awkward if there were no expectation of presents. I've seen 'reveals' on Facebook, and that is just sharing the joy, I think.
It's a new person coming into the world and an addition to a family though - not a 'surprise' treat. Babies are babies - and as someone said upthread, they are very uncomplaining about the odd bit of lace or a print with yachts or something instead of pink roses.
My mum had two girls and then a boy, and told me that people thought she should get rid of little cardigans as they 'buttoned up the wrong way'. I remember that continuing through to school ones, too. Perfectly serviceable grey cardigans couldn't be passed down as the buttons were on the 'wrong' side - madness. That has died out now (I don't even know which is 'the girls' way' and which the boys') and AFAIK nobody even noticed. I was perfectly happy for my daughter to wear my son's clothes if they fitted her and were in good condition, whichever way they buttoned up.