Should be unlocked similar to Halo 3, but somehow merged with a cR system. We should be able to color individual armor pieces, and put camo patterns on them. We should be able to choose whether we want our Spartan to look like a shiny toy, or a battle hardened soldier. We should be able to buy Assassination animations, and Player Model held weapons. And I think Visor Types would be interesting. Mix and match types of Visors(default, monicle, eyes, robo eye, ect).
We need new Visor Colors(red, purple, green, bronze, ODST Blue). We should be able to mix and match attachments. Forerunners and Brutes should be playable. And ALL races should have equal customization.
Well looks like you separated this ideas and made a new thread. 
Good ideas OP! ;D
I agree, the colours we have now in reach and cea are kinda lame in my opninion.
I’d prefer to simplify the armory to halo 3’s style, and maybe choose the colour of each armor piece, but that’s the limit. We already have too many people in matchmaking checking out the armory instead of voting for maps. Not only that, it would free up some disk space for other things.
While more customization sounds nice I’d much rather they save the disk space for more important things. If they did Halo 4 on two disks I could see it work with campaign on one and the multiplayer on another.
Other than that though I’d prefer the simpler style we had in Halo 3. At least those were iconic in their own way, not all this strange looking stuff we got in Reach that made your spartan look as if he’d just fallen into a pile of scrap.