Eh, I think the real issue is there simply aren't ENOUGH cosmetic rewards, and there aren't enough interesting different ways to get them. WoW had mini-pets and Mounts, some of which required specific tasks to get them, while GW2 atm really only has gear. I don't feel I need the carrot to be on the stick, but I feel like the carrot ANet is offering atm is a bit skimpy atm.
I feel you.
There needs to be more. And whomever up there, said it worked for GW1 cause of "PvP"... Dude, I didn't do any PvP GW1, EVER. And I thouroughly enough the endgame in GW1. I wanted to get certain weapons, I wanted to get certain armor looks. I wanted to farm. In this game, yes, I want to farm. But I also don't want to hit that DR.
So in other words, GW2, is sadly a gift that keeps on giving. There is too much DR, and too little funny and amazing moments to be had in farming and questing and dungeons to make it worth it.
Don't get me wrong, I *LOVE* GW2, I just wish it... was more. I can't put my finger on it, but there needs to be something done. So i'm looking forward to the changes coming in now, and we'll see. Atleast the Ascended armor(s) so far, has been a step in the right direction, though I'm not quite sure sticking it all into one dungeon was the right direction. That said, it's been said to be spread out, so we'll see.
But all those things above, combined with the convoluted economy of GW2 which is a bit hard to get by and get working for you, makes it... I dunno, I can see why people quit the game.