Id imagine there are more people doing quests and running instances than there are people doing pvp events which is typical of most MMOs. If they really wanted pvp, they probably would have played a pvp centric game like Dark Falls
I dont pvp, Ive learned my lesson regarding pvp. I stick to console shooters with normalized stats if I want to boost my game ego. If I want a single player experience where I explore overworlds and crawl inside dungeons for loot, I will play games like Neverwinter. I also play Dragons Dogma, which isnt an MMO.
Its the only MMO Im playing now. Ive gotten kind of annoyed by MMOs because of the time commitment needed to be "successful" at these sort of games. But the pve single player experience is fairly well conceived and the foundry keeps the game fresh. So I enjoy it from that perspective.
Assassins are always the most overplayed class because everyone wants to be the ninja. So that means there are going to be a shortage of healers and tanks in end game instances.