The Daily Grind: Short or long quest arcs?

A little while back, Beau from Spouse Aggro wrote a post about the fun of doing long quest arcs with cut-scenes in Dream of Mirror Online. While I can also say I've enjoyed questing in DOMO, sometimes there's something to be said for a quick "get in, get out" setup like, say, some of the one-off, well thought out missions I've seen created in the City of Heroes Mission Architect, or jumping in and doing something quick in Free Realms when you only have a short period of time. While there is a space for both, it almost seems like long quest arcs involving lots of time (and grinding) are becoming something of an endangered species. Games that have long time-requirements to complete them are often sparsely populated (as per Beau's mention of Final Fantasy XI) compared to many other MMOs on the market these days.

Thus, we raise the question - are long quest arcs full of "grind for x drop" "must complete with a group" "run all over the place for a while fetching things" slated to go the way of the dodo, with players instead opting for quick bite-sized missions instead? Or do you think longer quests are better, as they require you to get out into the world more and see/do things you wouldn't if you just ran outside the five-feet-away gates and knocked over 10 wolves for their paws then ran back?
This article was originally published on Massively.