Longer campaigns for single player ? Nah !

Kokugamer wants longer single player games.
Well, having finished "Darksiders" just recently, which I mastered in about 30 hours, and felt had some lengthty parts, I would tend to disagree.I would even dare say that I prefer shorter games, but it depends on the genre.
A game like Mass Effect, Fallout etc, RPG, RTSs, they can be longer, as there is a huge story arc and quite some levelling.
But a game like "Darksiders" could have been like 20 hours max for me, as I feel the whole story doesnt offer that much to justify 30 hours.
Lets face it, rarely a game offers such a dense and interesting story that You would want it to be stretched.
So I vote: no more than 20 hours max, or I get bored !