I don't think that he is talking about the story, which arguably was never good after WarCraft III, but adventuring in the world of the game like the older times, when travelling to a far-off zone to continue on a questline was an exciting journey filled with danger and mystery. The game has become too much about its instanced content and its repeatable content that could as well be instanced, rather than maintaining the one thing vanilla did right: offer a huge coherent world for players to... play in. We went from tenths of zones, multiple campaigns, class quests, off-the-beaten-path quest hubs, exploration and immersive gameplay, to five-to-seven zones, just two campaigns, a handful of group dungeons that are neither interesting nor big or complex, some by-luck exploration, and worst of all from playing to have fun and uncover some more of the world of the game to... gathering points.
And all that to make more instanced and repeatable content, and try and lure everyone that likes to PVE into that content because it is easier to make and cheaper. The problem is not the dailies; there are people that like them. Neither the challenging raid content; there are people that like it. The problem is that different people like different things. And the game seems to only focus on some of those things each time. Most players were quite happy playing out in the world in vanilla, doing some dungeon runs every now and then, and the occasional PVP. They liked it. And more of that would be fine. But the developers cut back on that type of content, by a lot, and tried to shoehorn everyone into dungeon running and raiding because it's easier to make such content. First they bribed them with some easy epics, mostly from PVP in Crusade. Then gave them a good foothold in raiding and more epics in WOTLK. Then, after failing to convince them to play better at the beginning of Cataclysm, they went on and even tried to get them into heroic modes. All the while the problem was that most of these players were not interested in raiding, and only did it because there was nothing else to do in the game. And now, well, they run out of options. Hence the boredom and the departures.
They should never have cut down on the overall amount of content they provided for the game. All aspects should have been treated equally. Questing, exploring, raiding, group dungeons, world PVP, battlegrounds, arenas, proffessions, role-playing; everything. And they had both the money and the time to do it. The game's phenomenal success offered them a stupidly high amount of money, and they should have invested more of that back into the game to keep it going. A game as big as World of WarCraft is extremely hard to renew normally, but their success was anything but normal. They had the chance to make something great of it and they blew it sadly. I really hope things get better, and all kinds of players are given the content that they want to play, but I don't see anything changing in the near future.