Amnesia: A Machine For Pigs Discussion Topic Part 1

[Googolplex]

I don't think a longer completion time is a good thing, just for the sake of it. Amnesia is very well paced. It's a short game, but it feels good because it knew not to drag things out.

Not every long game feels like it drags things out. There are a lot of games much longer than 60 hours without being obtuse at story.
I want to mention the old "Gothic" series or the adventure "Indiana Jones and the Infernal Machine" from 1999. It is very long, but never drag things out. To make a game longer means not it will automatically lose impact.

You are right, that most games failed by that, but as be can see from some other games, it is possible to fill a long game with interesting stuff.