What I mean is I loved how halo 3 handled the armor, you had no idea how to unlock them initially. You got them from achievements, finding skulls, and other things. This was AWESOME, it really brings the community together, looking for these treasures. I hate the feeling games have now days of “buy this -Yoink-” “unlock this -Yoink- for killing this guy 100 times” its dull and boring. This had been lost in today’s games, I miss the days of cheats and unlocking cool stuff instead of having to buy that -Yoink- as DLC. I want to feel like I’m really earning my armor and whatnot by doing something cool and memorable, not grinding for credits…
there should also be ‘viral’ armor pieces, and u h ave to play people who has it to get it,
and i like your idea 
Career milestones should play a bigger role in unlocking armor in Halo 4 as well.
I think that some armor should be unlocked by earning achievements or career milestones while the rest is unlocked by credits. IMO there should not be armor that is unlocked for getting a high ranking in a Ranked Playlist. (if there are any)
I respect your opinion but I really like the cR system Bungie made.