Abilities exclusive to Arena style?

So with al the complaining going around about ground pound and sprint and what not, i figured lets just find a solution. Now 343 may already be considering this, but hell, why not just leave this “Spartans have access to all abilities” in the Arena style multiplayer? When you go to play BTB or Team Slayer, it could be like Reach minus the armor lock, but maybe with all spartans having the ability to sprint and evade (just to make it different from 4). Spartans can then choose from Jetpack, Regen Field, Promethean Vision, and what not.