This is a proposal for Halo 4, assuming armor customization will return on the level of Halo Reach. The following will be written in the sense of Halo Reach, in an attempt to properly convey the idea and explain the possibilities.
Imagine a game mode, or string of game modes, that took every piece of armor you wore into account. Say, for example, with Jorge’s chest-piece (COLLAR/GRENADIER [UA]) as it has a large battery, heavy armor, and a plate extending above the neck, it would have the effect of increasing shield and armor capacity, or increasing shield recharge, while reducing speed similar to carrying a turret. With the Pilot helmit, as another example, with the UA/HUL[3] your radar may be enhanced in distance or detection, and that spot on your head may act like a grunt’s faceplate, needing to be shot twice. Perhaps the ASSAULT/BREACHER wrist attachment would increase shotgun clips you could carry, or extend their magazine size. A TACTICAL/TRAUMA KIT may allow a Spartan to fully regen health or hold a certain button to use it like a med-pack, maybe even use it to only heal teammates. Knee guards could increase speed and decrease armor, or increase armor and decrease speed. If your armor is the default, you would play as a normal Spartan.
Keep in mind that this would only be in one playlist/gametype/game mode, and maybe could just require one option to toggle in a custom gametype. This is purely for those who believe that the game requires a more tactical approach, and if Skulls return maybe there could even be a Skull that activates the armor settings in Campaign.
As a finishing thought, I encourage the community to post their ideas and thoughts on this topic. I left it rather simple to allow for expansion by either the developers or the community.
Your fellow fan,
max7238