No cosplay is not dead. It is something that absolutely anybody can do if they please. Everyone likes to play dress up now and then and sometimes dressing up as a favorite character is a form of empowerment.
You speak of perfect airbrushed women in costumes. That just means they are good at what they do. I don't deny that there could possibly exist women who pretend to be "nerds" and dress up all slutty to gain attention; but who cares if they do, really? It doesn't bother me. If it's something you like doing then go for it.
However, sometimes I feel bad for the people who like to send Jessica Nigri gifts. Have you ever seen one of her Mail Monday videos? Hundreds of people sending stuff they spent their own money on to somebody whom they don't even know in real life, based most likely on the fact that they are physically attracted to her.
Well long story short, cosplay is not dead. If anything I think it is growing. I won't get mad at "perfect air brushed women" cosplaying, just like I don't think professional baseball players killed baseball. I can't hold being good-looking against them.