My main activity in FFXIV is dungeons and usually with PUGs. I've seen some really shitty attitudes and behaviors since ARR launch.
Recently I have noticed an increase in what you describe. I play a healer and my husband a tank and we're both quite competent, but he usually doesn't pull unreasonable amounts of enemies. Despite this, the pulls/runs are always quick. I've noticed a lot of DPS trying to force speed runs by "subtly" aggroing additional groups of enemies without saying a word.
I've also seen a lot of people queuing for leveling parties and having zero patience for new players. This one makes me pretty sad.
I assume this is caused by a lot of people who are grinding tombstones/progression and becoming extremely impatient and tunnel visioned to their own needs.