I think these hit on one of the big reasons I eventually give up on MMOs in general. In WoW in particular, the game's mechanics alone were amusing enough for the first day or so of gameplay as my rogue was consistently getting new and exciting ways to introduce steel into poorly protected fleshy bits but eventually I found that every class settled into a routine pattern. I was told, of course, that the game was infinitely more interesting later on when I could go on raids as combat would suddenly become more varied and exciting but as an utter noob jumping in right after the Lich King expansion, that carrot was an awfully long way away. In the meantime I was treated to a largely single player experience.
In that time, I only saw other players when I ventured into town and even then it was only when I was in Ogrimar that I saw significant numbers of them. Of course, most of the denizens had already achieved the a status somewhere demi-god and beings so powerful they could sunder reality where they not careful when sneezing and as such their capricious activities were utterly lost on me. People would be trading in relative baubles and trinkets that were, alone, more powerful than everything I had ever acquired combined in forty levels of play. So, while they were other players in the technical sense, they had no impact on the game. Being an unsupported noob, even relatively noob friendly items and enchantments were so costly that I could not comfortably afford that incredible level 19 weapon or armor piece on the auction house until 20 (or more) levels later!
Thus I ventured the world alone. The combat, as I pointed out, ran out of entertainment value quickly enough. Worse still, as the game progressed I had less and less leeway in how I was going to approach a given battle and in many cases I was forced to take an incredibly tedious route to victory using abilities with long cool downs to make up for my lack of a group. While the story might be a draw for some, there wasn't really any reward in it. I was appointed a defender of this or a champion of that and I would embark on suicide missions for the sake of the Hoard, but once I was done nothing tangible would change. Sure, I'd get a few coins, some experience and an item that I was almost certainly going to convert to coins at the earliest opportunity but that is hardly a tangible change.
Still, I managed to soldier on. After about 5 months of play I had managed to finally claw my way to the same scrap of frozen earth that the bulk of the player base was busy cleansing of all life (or un-life). Still, the game remained largely a single player experience. Many who had not reached the apex were shockingly well equipped - I assume as a result of rolling new characters bankrolled by old veterans and few wanted to be in the presence of a Rogue built for a solo adventure ring career. I could hardly afford to respec on a whim, both in terms of skill distribution and gear. Where other players were equipped with items of peak possible power for their level, I was often making do with something I found many levels prior and thus, even when surrounded by comparably leveled players I was still playing a different game.
I had slogged through Azeroth long after the game mechanics became dull and boring for the promise of actually seeing people regularly in Outland. I had soldiered through that ruined hell-scape because I was tantalizingly close to being able to survive in the same geographic space as most of the player base. But when I finally got there, it became apparent that my long journey (more than 5 days to get to level 70 if I'm not mistaken) was not even close to the end I was promised months prior. The brutal level of grind only increased further and the narrative continued with the same urgency as before except now that I was at the vanguard of the stories battles it seemed even more absurd. Now I could watch a dozen heroes valiantly repel an attack before doing it myself. Now I wandered past a desperate offensive I would soon take part in. The story itself was compromised not only by the inherent fact that the game world could not change as a result of my action but by the fact that it couldn't change by the actions of others.
I might still have kept going, but the promise of playing with friends at the end game, the very thing that convinced me to start on the journey in the first place, evaporated soon after I reached that miserable pile of ice and blood. After more than six days of play, after turning the tide of many a hopeless battle (only to have it reset mere moments after I left), after slogging through 74 levels when no substantial new ability was given to me after level 30 I gave up.