RE: why should down mean up?
Earl, you are holding your transmitter wrong... or maybe I should say, "You're not holding your transmitter the way everyone else does"
The Tx should be held relatively flat, not standing up.
This makes the stick movement forward and back, not up and down.
Now by all means, you may set it up anyway you like, but you will never be able to fly someone elses plane nor could they fly yours.
But beyond that, it's just something that's not done. It's like wearing shoes on your ears because your ears are cold but your feet are not.