Halo 4 Bumper Jumper Control Scheme Changes

I have used these controls since Halo 3 and Im sure i wont be able to get used to any other. Why is X to throw nades? And why is LT used for AA? This is what i think the controls should be:
LT = nades
x = sprint
A = other AA

That is EXACTLY what I was thinking. This would be a good bumper jumper. Than use D-Pas for switching between plasma and frag