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"
"You do not know the first note of the music that moves me."