The truth is that many players need "lolSomething" to laugh at to make themselves feel better. It's a comfort to them to know someone else is being made fun of, and not them. "At least it's not me."

Second, most of those same players are simply blindly repeating what they hear on teh internetz without actually looking into what they are repeating for themselves. So, most of them don't really know why they are saying "lolDRG" other than because it's what everyone else is doing.

Third, DRG is one of the more complicated jobs to master (having played most of them myself), but at the same time, very easy to be "passable." This means that you will have a much higher ratio of players who hit the "decent" mark, and very few who hit the "amazing" mark. Take BLM, for example: They can hit the top of their performance very easily. Someone would have to be completely stupid not to get the most out of their potential. So, the FFXIV world at large is typically only going to see the DRG players who are doing just the bare minimum to get by. These same players are usually those who don't avoid AoEs, get locked in Jump at the wrong time, all while using Blood for Blood.

Fourth, it is almost always easier to pin-point the bad players from the amazing ones. No one see's a good DPS when they are doing their job. The group is making their dps checks, the tank isn't fighting against poorly managed front-loading hate, the healers aren't watching the dps who can't avoid AoE's, etc. No one is watching other people close enough to know that you are doing your rotation correctly. They just see when you make a mistake and wipe the party.

Finally, I have personally cleared t1-t9 as a DRG, each time before the Echos came into play. I can tell you that DRG does just fine. In fact, the few times I have missed a raid night, my team has told me that they never realized just how much of the DPS I was adding until I wasn't there anymore. Played correctly, it takes a seriously good player to out-perform a well-played DRG.

Unfortunately, however, this means any failure to perform is on you, not the class.