I think the social playlists are structured VERY poorly and something needs to change in the future. Heres a suggestion:
4v4 Slayer
4v4 Arena (King of the Hill, Strongholds, Capture the Flag, One Flag, Attrition, Oddball, Land Grab)
4v4 Action Sack (Snipers, Fiesta, Vampire Oddball, Ninja Slayer, Rocket Repulsors, Skewer Mayhem, Tactical Slayer, Shottys and Snipers, Crazy King, etc.)
FFA Slayer
FFA Action Sack (Snipers, Fiesta, Vampire Oddball, Shottys and Snipers, Rocket Repulsors, Ninja Slayer, Escalation Slayer, Skewer Mayhem)
Doubles Slayer
Doubles Action Sack (Snipers, Fiesta, Shottys and Snipers, Vampireball, Rocket Repulsors, Ninja Slayer, Skewer Mayhem, Tactical Slayer)
Big Team Battle
Last Spartan Standing
FFA
Doubles(?)
All Action Sack playlists would allow you to choose which modes you want to include in your search (Like MCC) and the slayer and arena playlists would be standard AR/Sidekick social playlists.
Obviously this may not be the perfect solution but I feel that changing it to something like this would largely benefit the game. It would give more options AND variety and allow players to choose exactly what they want to play.