Hmm i haven't noticed this, i'm at the same level (88) and as a frost mage i'm usually doing the lowest damage done at about 25k dps. Then again i tend to move around a lot to practice avoiding damage so my activity is also usually the lowest. I usually see people reaching ~35k dps in the dungeons i've been doing, the top offenders being enhance and ferals. Hopefully once i get my lvl 90 talent (all which sound horrible to use) i'll leave these guys in the dust, but whatever, i pvp 80% of the time.

Also keep in mind that there is an absolutely huge gear gap at level 88. There are people with 372 weapons going up against people with 450 weapons, on a caster weapon that's about 2k difference in spell power.

Then there is the fact that you don't need to be pulling high level dps in dungeons, or do anything. Compare this to BC where even the highest dpsers in your party could get kicked for failing at combat mechanics and CC, now it's just like meh whatever, even if someone is doing less dps than the healer people don't care. This mentality is only really hurting the quality of players that are coming through to lvl 90.

In the cases of newer players they've gone through 'vanilla' dungeons where the tank has been doing 80% of the damage done and the dungeon is finished in ~10 mins. You can't really expect them to somehow learn late game concepts from this model. Half of them probably wouldn't even know how to maximise their dps as the tank has been 2 shotting mobs before they can get a 2 second cast off, thus you see a lot of people resorting to instant casts, mages continuously spamming icelance etc.