I never minded those "1st room only" runs even if I never cared to do that myself... As long as it's done via party finder, to get a full group of like-minded, I think it's a great thing. But to go in via DF and then just leave once you got what you came for? Not even counting the 30 minute lockout for leaving (which doesn't really sound efficient), that's a really shitty thing to do when you don't know if the others in the group are there for the same reason.

That said, I still think it's a pretty good change. Personally, I've never minded the "slaughter everything in sight" approach if there are two or more in the group still levelling -- I ended up in Brayflox normal the other day on a low roulette with three levelling people, and we killed everything. (I do ask people "go straight for the boss, or kill everything for moar exp?", and if people say "straight to boss, please", I'll go with that of course.) But I can understand that not everyone is of that opinion and would rather skip as many of the mobs as possible to make it a shorter run. And for those runs, the people still levelling now get more exp than they would have previously.