I kinda agree with you, but I want to add something. I love wearing black in my normal life, and your larp costume needs to look like it's a costume but rather clothing... But why would I wear all black? Everyone is wearing all black or black/brown, I want people to remember me and I want them to recognize me from my colour coding (I don't do much sneaking so that's okay for me lmao). I resorted to wear a red/black jacket, red beret, blue shirt, black trousers, brown armour and a tartan green/red/gold sash with some fake fur. It's bright, it's colourful, I received lots of compliments.

I do agree that with another character or setting wearing more black would make sense, tho!