One of the most interesting mechanics I've ever seen in an online game is changing bosses. Randomly changing boss encounters, rare boss/mini encounters with rare loot. It keeps things fresh. One of my biggest pet peeves as a healer is someone ignoring mechanics/AOEs in raids just to squeeze out an extra 1% dps. As a healer if Im having to heal DPS standing in aoes just so they can squeeze out that extra 1% I'm not able to dps half as much and I'm pretty sure 50% of my DPS is greater then their net gain of 1%. And of course a dead DPS is no DPS. Yet if I don't heal them they talk trash. Sure it's rare you get those types of DPS but that's my point the game teaches them to ignore it because the content is old and everyone wants to burn through it asap.