Hello everyone!
Well, I don’t think I have to introduce the problem. We know it since Reach and it is pops up in Halo 4 too. Older DLC maps are nearly unaccessible in matchmaking because there is no special play list or requirement for them.
Well, my advice is to make a play list that rotate four times per month. We got 3 map packs and 4 weeks per month, so at the first week of every month there is should be a play list for Crimson maps, at the second the selection is the Majestic, and then the Castle. For the 4th week, they should include some community forge maps. Then we have 6v6 Crimson and Castle per month, and 4v4 Majestic and Community Creations.
Game types can be tweaked to fit with the play list, but the biggest complains are about the maps.
Simple, easy and enjoyable. I know 343 is busy now, but it’d be nice if they see this idea and hopefully they will integrate it into matchmaking. With it, everyone can won. Map Pass holders will be happy, probably more players will be interested in map packs, forgers can take the challenge and we’d be proud of you 343, proud of playing a Halo game that you made. This system is maybe not that easy to build as I think but, you can make it work!
What do you guys think about it?
I like the idea of a rotational DLC playlist - they may well do this once Castle has been out for a while.
I think your idea would work but I would prefer of one of the weeks was all community maps and not mixed with a map pack, ie: crimson, then majestic, then castle, then community forge.
I also think a permanent 5v5 playlist could house all the DLC at the same time, but the limitation would be only objective would really work on the largest maps.
My preferred solution would be about 2/3rds of the playlists simply having DLC requirement whether for one map pack or another.
Well, forgive me if I was a little bit understandable English isn’t my native language. Nice to see you likes my options. 
Actually, I also think about 5v5 in general but Castle and Crimson play lists were 6v6. I think it was the perfect team size for them it were feels right on those maps. Majestic was 4v4, those maps are designed for it. Most of the community maps are made for 4v4, so it’s fits great with Majestic’s team size.
Running all the maps at the same time would causes one of them will be overplayed while others became unpopular.
For game types I think, Crimson & Castle play lists could feature Dominion while Majestic and Forge maps could run some FFA. Also some sort of FFA Objective would be tasty.
Matchmaking could prioritizing bringing players together with DLC, and then make DLC maps more common in voting. I’m not saying that would be easy or possible. A change like that, however, would be preferrabe to segmenting the population with more playlists.