I just want to preface this by saying two things.
1) I have never played a warrior.
2) I do not wish to play a warrior.
However, as a general player I have a tremendous amount of concern for what having warriors as a somewhat mediocre DPS in dungeons could mean. I understand that, at higher levels, their DPS becomes reasonably useful and even though they're not a top pick, they at least serve some purpose. However, I find this to be insufficient.
The simple fact is this game was intended to have 2 tanks, 2 melee dps, 2 healers, and 2 ranged. It's been understood that, due to the nature of the warrior and their usual audience, that they need to have decently high DPS (more than the healers and Lancer) to really be any fun. So they got the DPS buff, which I approve of. It makes more people enjoy the game, so it's a good change.
The problem is that Lancers are -still- the only tank that any group was interested in having past a certain level. This is going to cause a few things...
1) Groups are harder to find as all groups must have Lancers.
2) Lancers will accelerate and acquire gear faster than most other classes because they will always be able to find groups due to being the one essential class for group content.
At this point, it seems very strange to me that nothing has been done to make warriors more appealing as tanks in PvE. I understand a very specific set of class abilities, animations, and general concepts (the dodgy tank) have been laid out, and these won't change in time for launch.
So, at this point, I think you should just put a band-aid on the issue until a more competent solution is found. Give warriors a passive that reduces all the damage they take from BAMs or something similar. Give them a PvE tanking buff that won't make them any tougher in PvP (cause to be honest, warriors seem to be fine in PvP and I doubt they need buffs for this.)
I feel this would solve a lot of issues, especially the one of sitting in LFG looking for a Lancer ad nauseum. I mean, yes, this would make warriors the one class with multiple roles available to it for a dungeon run, but it seems to me like far more people would benefit from this change than be disadvantaged. (Except maybe a few Lancers who have to wait 2-3 mins to find a group.)