Sure, it's tradition... but so is bullfighting - does that make it "right?"
I'm just saying some things could stand to change - right now people are completely abusing the bits they are "made" to use. I see absolutely NO reason there is a need for double bridles other than tradition. In my personal, very humble opinion, if you can do all this in a snaffle, why not do it? The idea behind the double bridle in the first place is just to use the curb when you need it, but that doesn't seem to happen much, it gets ridden on a lot.
I do have to giggle at ridergirl23's response - it's probably a little true ;)