I do not really understand how DMR gametypes promote camping. In fact, power weapons are a great way to dislodge campers. I have played tens of thousands of multiplayer matches throughout Halo's history. Camping has never really been a viable tactic. Maybe if you get the sword or shotty you can manage a few cheap kills, but anyone with a little bit of awareness can easily dispose of a camper in Halo.
I can maybe see what you are saying, in the sense that DMR gametypes can promote map control, as in holding a certain area if you have the power weapons. But this strategy is a) rarely used in TS and b)can also apply to AR starts, especially if the pistol is a secondary weapon. I really do not want to sound like an elitest prick....but sometimes i think that people are just scared to play with DMRs, because pacing headshots is much more difficult than holding down a trigger (pump firing if you know what you are doing).
Halo multiplayer is what it is today because of precision weapons, mainly the Halo 1 pistol. While I do not think TS should always be DMRs, at the least people should have the decency to stay when it does get voted. As for its own playlist, I could agree with that. But I do not agree with that so Elite Slayer will show up. Honestly, Elite Slayer should have its own playlist to give DMR gametypes more love in TS.