Well... I don't know.
Obviously, nobody should be made to feel less-than because they are a certain way, particularly since nobody can be hurt by this. There's a certain standard of respect you should have for people and telling them they're "wrong in the brain" falls well behind that standard. That being said, it IS a chemical thing. So is being straight, gay, bisexual etc. Everything you are is a mix of chemical reactions and electrical impulses. There's nothing inherently wrong about that, it just is what it is. W
here asexuality is different is it's not a different form of something, it's the absence of something. It's like never being able to see a specific color: You may be perfectly happy without yellow, even think your pallete is less complicated by it, but how do you know you wouldn't be happier with yellow in your life? At least, if you are asexual by birth and not by choice.
It's probable that I'll never understand because it's impossible to put myself in their shoes, but from a purely detached, logical perspective, it's hard to reconcile.