I actually notice people's armor quite often. People pay attention as close as they want to, some would notice, others wouldn't.
Don't say that to loud, 343i might be watching and have to put bigger grinds for more necessary features to force you to grind. Personally I cbf to unlock or grind anything in Halo 4 because soon as Halo 5 comes out everyone's gonna be grinding to unlock things in Halo 5 and no one including most of the players that spent there time grinding In halo 4 no one will give one single care about what commendations or armor or anything you have unlocked in Halo 4. Then when people start grinding in Halo 6 people won't care about what you unlocked in halo 5(and specially not what you unlocked in Halo 4) I use to grind in Halo 4 until I realized I was just playing to unlock useless commendations/armor(seriously think back to playing Halo 4, How much of it involves trying to unlock commendation's or armor or specialization's, Which will all be useless when Halo 5 comes out) and then I tried to play the game without grinding and I honestly couldn't enjoy myself because gameplay is subpar and personally it ruined a lot of what I enjoyed about Halo though glitches/bugs/unbalanced things and intentional choices. So guess I'm never getting that armor. Meh.