while old content may not always drop great loot, theres a couple of good reasons to do it. as sath said, quest lines,not to mention unique clickies that can be had, but also, experience. stuff a few years ago, while the mobs themselves may be trivial, the strat required is not. raiding isnt just about apply dps and win. alot of times, there will have to be multiple small forces, working independently, with little or no direction. knowing your job can make or break a raid. the events in places like death knell or ashengate, let alone some of the stuff in mmm or crystalos, while easy when done right, take very little error to lose. nice to have a chance to get used to raid mechanics without dying so easily for those new to raiding