If anything, I'd say the percentile requirements for mainstream content are actually the opposite way round. DPS only really get held to account once you hit Savage. I've never seen enrage on Lakshmi (granted I also very rarely bother pugging it) and I've maybe seen enrage on Susano once? As I noted in another thread here, you almost need to be trolling to cause a genuine issue in a dungeon as a DPS now.

By comparison, a fresh 60 healing SB's current expert dungeon needs to have a pretty good idea of how their oGCDs and cooldowns work if they want to keep up with a tank intending to pull more than a pack at a time.

Whilst my sample size is too small to draw any real conclusion from, if I look back over my logs, the standard of DPS seems to be going backwards again, whilst most pug healers I get have actually been pretty decent.