|Sit back, m'boy. This is gonna take a while.|
For my criticism of WoW to make the most sense, first I need to talk about what there is to do in WoW. (On a side-note, none of this applies to PvP. That game really doesn't change too dramatically.)
See the rest below the jump.
The gameplay in WoW can be generally broken up into two categories: Leveling and Level-cap. When you start a new character, you're leveling: You're out in the world, exploring, questing, delving into dungeons. You might also be increasing your skills in various professions. Once you hit the level cap, you're likely done with the quests and have gathered as much gear as you can from dungeons. Most players, at this point, jump into raiding. Most raid instances reset on a weekly basis, and most players can only gather to raid a few nights a week. Some people play the game every day; what do they do if they can't raid?
When WoW was first released, there wasn't really much else to do. You could increase your reputation with some factions by grinding out ridiculous numbers of mobs. You could join in on PvP matches. You could just start another character. I'm probably missing out on some things, mostly because I didn't play the game during this era. The point is that Blizzard saw there was a gap for players who played every day. Starting in the second expansion, Blizzard added daily quests, which reset daily (as the name implies). This gives players something they can do every day, on top of the other activities available in the game.
Daily quests offered quite a bit besides simply being something to do. Most daily quests were tied to factions, and completing them would earn reputation. When you reputation was high enough, the factions would offer equipment, profession recipes, and cosmetic boons like pets, mounts, and tabards. Some factions acted as gateways to other content, such as heroic dungeons or raid attunements.
WoW is currently in its fourth expansion. If you're new to the game, or even just relatively new, its heartening to know that you can still see much of the content from the previous expansions. You can still go back to run the dungeons and raids from the older expansions; if you're at a high enough level, you can probably run it alone.
You're probably not running the dailies, though. Perhaps you want the cosmetic rewards, or perhaps you're just an achievement junkie. Still, going back to run old content, day after day, feels very different from doing the same thing on current content.
In the current expansion, there are roughly 16 factions you can earn reputation with, 11 of them have dailies, and most of those include story elements with the quests. If somebody returns to Pandaria two or three expansions from now, how much are they going to put up with in order to get the story of the place and what happened there? If the "important" story can be gathered without doing the faction daily quests, then why is Blizzard having us bother with it now?
In short, dailies are what's wrong with WoW, but from a long-term perspective. Locking content behind daily quests limits the appeal of that content in the long term, on top of being obnoxious to players who can't play every day. I'm not sure I have a good suggestion for alternative content, but Blizzard ought to consider a different path in the future.