I don't have any problems with it.
I think it's another part of the combat of wits.
We all know that while playing we should pay attention to what our opponent is doing, and if we allow ourselves to be fooled by someone who is walking in the wrong direction AND is still wearing his armband during a tourney, then we deserve it. I personally think a DMW is not bending the rules, it's actually quite gutsy. I mean, we all see it happen that players who are eliminated get shot anyway, even when they are walking with their hands up. Hell, we all shot the odd ref or two as well. A person going on a DMW is breaking cover, exposing himself in a way that no one in his right mind would do, just inviting some front player with an electro to pop up and hose him with 25 shots from painfully short ranges.
In my opinion, if a team falls for a DMW, it's the back player's fault, he should be aware of eliminations on the other team, and he should pay attention to the behaviour of anybody on the field, so if he sees someone walking around, gun in the air, with armband still on, going the wrong way, no ref running up to him, and this person still manages to take out some people, don't start bitching about the legitimacy of DMWs, burn your backplayer(s) at the stake instead! When you sum up all these factors that can identify a DMW, you have to admit that the person going on a DMW is a brave person indeed.
P.S. I also think that DMW's have no, or very little place in rec-ball. Shame on you Tyger (jus' kiddin').