Right thumb is getting way overworked there. Try pushing B and X at the same time, or operating the joystick while pressing anything. Not gonna happen.
At this point they should just start putting out keyboards instead of controllers. No matter how they design these things, you\'re always going to have 6 perfectly good fingers wasting their time.
I used to play Descent on the computer, and I created an insane keyboard setup where, using all 10 fingers, you could operate 14 buttons simultaneously. (Four of your fingers were responsible for 2 opposite keys, such as up and down, that\'s how you operate 14 buttons with 10 fingers.)