Just popped in Rage and was immediately blown away by the separately adjustable X and Y axis-sensitivity. For me, it only makes sense. I would like to be able to turn as fast as I possibly can, but can never set it for such as it completely affects my aim vertically in a very bad way. I don’t see the point in them being tied together in Halo as that only limits the possibilities and effectively makes you choose between accuracy and turn-ability/being more vulnerable from the sides/behind.
With the new focus on “perks” to customize personal play-style, how about more customization on the control-side to achieve the same?? In fact, being able to remap every button would be a nice addition to the series as well imo, but separate x and y sensitivity would be a fantastic start 
Thanks for listening 343!