It would be interesting if in future games we were given a more three-dimensional control over thrusting, similar to how it’s used in cutscenes. To be more specific: if the player looks down and thrusts backwards, they would move up, and vice versa.
This would give players more situations in which they might want to think about using up one unit of thrust: if they want to get extra vertical acceleration to avoid a splatter, or if they need to get down behind cover. It would also potentially enable more mobility in zero-g without having to rely on the ground pound, which could be great for campaign missions or fun gametypes.
This is no small thing, as of course a lot of things in the game would have to be balanced around it, but I think it’s worth it for the extra dimension it would bring to the thruster pack, making it feel more fully-realized.
This could also be extended to the spartan charge, though obviously some allowance would have to be made to prevent people from accidentally charging into the floor or sloped surfaces.