[Rezz]

I think it largely depends on the size of the questlines involved, the leveling rate and a slew of other factors. I agree that content creation speed is the issue, but I can't really think of a game that's stayed ahead of that curve without artificial cockblockery.

The game could offer toned down repeat events for people to deal with if they want to see what happened when a zone first got opened as one type of event. For example:

You're level 5, it's taken you 4 hours to get here, and you've completed a few quests, one of which seems to lead you to eventually killing the orc boss. You follow up on the quest line as much as possible, doing the exact opposite of kill/fed ex quests at this point. Each quest is to kill a single named mob in a different area of the orc lands outside the orc fortress. You gain the majority of your xp from having to kill towards these orcs, maybe with an xp bonus since you are on the quest (another idea, will expand after example.) Each one you kill completes your quest and gives you part of a progressive item that eventually unlocks the door to the fortress. These are all solo quests, the camp is spread out and the orc minibosses only drop loot if you are on the quest to kill them and haven't killed them yet. You complete the key, upon hand in a couple orcs bum rush the Bob Orc-Slaying-Questgiver, you defend him, he tells you to go slay their leader. You head to the fortress, killing a couple orcs on the way there (again, solo designed area so shit's spread out) and when you reach the gate you find the Gatemaster Orc who summons wargs to attack you. They're a pretty beefy challenge, but still doable if you are the right level with the upgrades from the orc minibosses. He gets off his mount and attacks you, same difficulty as the orc minibosses that you are now outclassing. All done solo. Now Orc'Gar the dungeon is open. If a player comes after you, he has to do all the normal sub quests, but the orcs no longer drop the key parts. When they get to the gatemaster portion, instead it's a slightly toned down encounter with a warg keeper guy and his warg pups. You have the same gear from killing the minibosses, but the fight itself has slightly less hp, does slightly less damage.

I think the actual content speed issues and people missing things will only happen at the low end really, as the speed at which people progress is faster in the early levels, and by keeping a somewhat expanding leveling range you will have more people at the appropriate steps as you leave the low-mid level range to see the grand opening events.

Now, back to the other idea I mentioned about bonus xp while on a quest, I think it's a potentially viable alternative to generic "kill 10x" quests. When you get the quest to slay the orc chieftan, every kill you make inside the orc dungeon gives you a small amount of bonus xp up to a certain point. Or bonus skillgain, or bonus whatever. Leveling isn't going anyway anytime soon though =/ Anyway, these quests could simply work off monster/zone type. If you are sent to kill the orc chieftan, for every orc inside his stronghold you get a 5-15% bonus xp. This could be visible in the UI or not, but it does run out after a period of time/number of kills/amount of xp earned. Whichever. Granted, this would alleviate the quest log issues as you wouldn't have those kill quests in there. You could also simply make it so that you can't drop quests, but you get an infinite number of slots for quests.

Personally, I like the concept of some named npcs in a dungeon only dropping loot if you are on some quest to slay them. This would alleviate the concept of farming to a degree. Just make these npcs always drop certain items. Which gets into my next idea that "rares" should always drop one item, like they do now. But instead of a more rare item possibly taking place of the lower rarity item when you kill it, he drops it in addition to. Take the ghoul lord in Lguk. He drops the SSB the majority of the time, how does it take away from his ability to wield the SSOY? He "always" drops the barbute in my system, with the chance to drop both barbute and sword. Or if he had another rare on his table, he could drop up to 3 items at once. This goes with the "moar loot!" idea.

Brainstorm, so to speak.

edit - was a reply to Draegen for the most part