True, no one likes finishing a fight, being low on HP and then getting offed by someone who just arrived on the scene. But that happens in every mode. You gotta learn how to avoid that situation.
DM is the most fun for me simply because there is no pressure from anyone but myself to do well. There is no one else to blame if I lose. If I want to yolo dive all match, fine. If I want to play a mech I suck at, fine. If I want to just do stupid stuff and mess around, fine. I don't have to listen to some skrub telling me where to go, or what i should be doing, or bitching about how bad their team is...
If you are worried about your stats, DM is probably not for you because odds are you are going to lose. Team mode its 50/50 chance of winning. DM is 1/12. Also, if you have a 2400+ mmr but never play DM then you are probably not really a 2400+ player as you have 5 other people helping you out in team modes, DM is all you. Support mechs don't do that well in DM.
Those of you who complain about two people working together think of it like this: you have more targets than they do. Most of the time people teaming in DM do NOT win the match because they have fewer scoring opportunities.
And there is nothing like killing enemy after enemy, even when they start teaming up. Pulling off a nice kill streak against a stream of full health opponents is awesome and just makes you want to throw a holo and tea bag their smoldering piles of mech remains before walking away.
Also, NEVER be the mech in the middle. You will die first. And shoot everyone, those assist points add up. Sometimes I will just simply shoot everyone i see and then run away and heal while they kill each other, then i go back and shoot the survivors. (Yes, I am that fuzzy bunny Scout...)