I really miss playing as an elite since Reach. This spartan-only, Infinity-based, war games canonical excuses have really been bothering me since Halo 4. I don't even care if it's in social playlists only, other community members have already said all there is to say about this topic. Personally I'm getting bored of playing as a human in every single first person shooter game and halo multiplayer is something I really enjoyed because I could play as an elite. It's a genre that's getting stale in terms os characters because of this very problem: human characters.
(On another topic, playing as a flood combat form, or brute, or promethean soldier would be pretty cool too, but that would require much more work than elites. )