As in: I'd like to be able to move in the horizontal direction that my hip points toward, not wherever i'm looking, so i can look around while still going forward, without having to adjust my thumbstick constantly.
Also so i don't start moving backwards when i look down or up and accidentally move past the 90 degree mark, which is ridiculous.
Of course it would require a mechanism to prevent the behavior described above if the hip is pointing up/down/slightly further too.
While you're at it, you can also add moving in the direction that you point with your left/right controller, which i personally dislike, but some people use it in games where they can.