Ferrel argues that MMORPG's would be better off if it took longer to reach the game's level cap, with an increased focus on the middle game to ensure that it was actually fun to remain at those level ranges. I agree, though I'd also argue that this is largely like saying that higher quality would make games better. The more interesting question is this - why have games strayed from that path in the first place?
Why Rush The Cap?
The current rush to level has more to do with the need to get new characters (whether newbies or veteran alts) up to where other players are for grouping than any intrinsic desire to have players hit cap quickly. At least until WoW's cross-server automated group finder, no developer had found an effective answer to the question of "who will the level 40's group with when the majority of the playerbase is level 80?"
The hope is that accelerated leveling will get newbies to the cap fast enough to help balance out attrition among endgame guilds. As an added, if secondary, bonus, less total time spent leveling means less time spent on those pesky middle levels, which tend to be the thinnest on content these days.
At the end of the day, the actual rate at which the arbitrary level number by the player's head advances doesn't really matter. What matters is whether the player is having fun while playing the game. This is where it's no accident that the rise of solo play coincided with the rise of the WoW-style quest.
The Solo Quest And the Grind
Ferrel finds the solo quest path boring - to be precise, he describes them as:
"Boring, mindless, pointless, chores that your boss gives you at work because he sees you sitting still for one minute and cannot handle that fact."
This is actually a tangentially related problem to the time it takes to reach the level cap.
Grinding in a group, like the EQ1 groups Ferrel reminisces about, provides both entertainment (e.g. joking with your friends) and unpredictability (e.g. someone screwed up and suddenly there are a dozen mobs eating your corpses) to an otherwise trivial task of chain pulling identical mobs. If you think solo quests are boring, you should try solo grinding (e.g. LOTRO's "kill 300 mobs for +2 agility" kill deeds) sometime.
In the absence of other players to supplement the fun, Blizzard came up with the guided tour of Azeroth. The point of the quest is straightforward - encourage the player to change the scenery before they can get bored of hacking away at the same mobs solo. The large chunk of experience for completing quests is basically reimbursement for players' travel time, while the hope is that slight variations in mobs and environments between quest areas will keep players entertained.
In terms of gameplay, this is no different from standing still in one location killing the mobs (or, for that matter, walking in a straight path killing mobs, as you will often find in a single player RPG), but - if and only if the developer has the resources to create a world large enough to sustain the model - the feeling is that the player is on a guided tour through a large world.
Supporting the world
Unfortunately, as I've written in the past, it is nigh impossible to actually generate content fast enough to sustain this model. If most players are spending an entire level grinding at a specific camp, the game only needs one or two grinding spots per level. In fact, having more choices can be problematic if it splits the grouping pool and makes it harder for players to agree on where they want to go. This leaves a lot of room to spare for optional content, exploration, while still producing way less content per level (and therefore spending less in development time/money).
By contrast, the entire point of the scenery-changing quest model is that players should change locations after some approximately fixed period of time before they get bored, no matter how many times that has to happen each level. This drives the resources needed to support that playstyle through the roof, to the point where not even Blizzard can fully support WoW style questing. (See the forthcoming Cataclysm expansion, which is, in part, motivated by the hope that sprinkling in new leveling content will encourage players to use the remaining older content in between revised areas.)
Ultimately, this is where the tangent of solo quest structure comes back to affect leveling pace. Some portion of the level acceleration comes because developers end up tuning the exp curve around players hitting max level by the time they run out of the game's limited content.
Mixing the solo and the group
Personally, I think there still is value for both sides in having solo and group players co-exist within the same game. Solo players get a larger world than is typically possible in a single player game, along with the option to access the multiplayer aspects of the world (especially a more robust economy) if they choose. Group players get the higher all-around production values that are made possible by a broader audience. That said, there is also room for conflict, a conflict only becomes more pronounced as aging games get less and less new content over time.
At the end of the day, I think that there is plenty of room in the market right now for a game to take the Darkfall approach to PVE. Players may need to adjust their expectations for such a game, bearing in mind that Darkfall's rocky launch was actually a FEATURE that allowed them to keep their development costs low enough to write off the solo market, but this should be well within possibility as long as the investors go in with realistic expectations and deep enough pockets.
If anything, I think that the resurgence of the group model with less total content and longer leveling times may have a brighter future in the short term than solo PVE. As many games have demonstrated over the last few years, just tacking on a few solo quests is not enough to retain players who expect both WoW-level quality and quantity from day one. This entry barrier may now be too high for anyone to overcome. If you can't do solo content better than WoW, you might very well be better off not trying to do it at all.