Beating up rat after rat after rat is a boring job for obsessive-compulsives. Most of us put up with that as filler, to see the next piece of the story, get the next reassurance that we're the great saviour of the furbolg race, or just the next achievement.
What passes for content otherwise in these games is a boring job for obsessive-compulsives too. The stories are very simple and hours of gameplay can be condensed into maybe a paragraph of actual events. Killing a hard boss for the first time maybe, but mostly the fights are predictable enough that even the slow folks get it with enough repetition. Evenly matched PvP fights sure, but most MMOs are set up that you're always facing a gear or numbers disparity.
I kind of prefer an honest grind to one with a thin layer of delusion covering it. I mean in EQ1 for a hardcore grind group you'd need to break an area using all kinds of pulling techniques, and if you got too many in camp at once by accident your group would need to go into overdrive throwing out mezzes and debuffs and heals, maybe offtanking. Interaction with other players meant all this was never entirely under your control. In a way it was more challenging than some of the scripted boss fights these days.
Understanding is always the understanding of a smaller problem in relation to a bigger problem. -- P.D. Ouspensky