As suggested by Lantz, I think gamers are generally savvy enough to have some idea of what they’re getting into when they buy a game. They know Dragon’s Age isn’t going to be over nearly as quickly as, say, Gears of War (not counting multiplayer); much the same as a filmgoer probably isn’t surprised when Saving Private Ryan is twice as long as Sausage Party.

Also, as mentioned, the average gamer is 30–37, most of whom have almost certainly spent several years up to that age playing games and accruing the experience necessary to judge for themselves.

All to say I’m not sure if length is really a necessary metric for most gamers. (You still make some interesting points)