Some games are definitely too short, while others overstay their welcome. A game needs to be paced for what it is.
Take a game like Kingdoms of Amalur, that game has 200+ hours of content I'd say, but the game isn't fun for 200+ hours. For 10-15 hours the game is fun, so within that 10-15 hours I should beat the game and feel completed, but no, that isn't the case here. I'll never beat that game or feel satisfied 'cause it overstays its welcome.
I'd much rather a solid 10 hour game paced perfectly for 10 hours, than a 200 hour game that is paced for 10 hours.
"You lack the requisite spine and testicular fortitude to study under me"