There are at least short term dps checks too thrown into fights to be fair. Granted these usually take the form of 'kill adds before bar fills' but they're there. Sometimes they're more fun than that like O12 where you have to take down Omega M for his barrior to drop before Omega F finishes a big spell, but usually it's just the adds.

As for the defense stat, I don't really see the benefit. Part of the fun of an RPG is seeing your numbers get bigger as you level up and get better gear. Maybe the numbers are getting crazy and they would need to do a stat squish like WoW has in the past to bring the numbers down, but using a defense stat so that your damage numbers in one tier are the same as they were during the prior patch would just feel kinda lame.