I chose 5 hours as if the game is great fun or has replayability then I'll get my moneys worth. Your article doesn't really take into account games without a "campaign". Sports titles for example, or games like Rock Band. I completed most of the Guitar Hero games inside a hour or two but then would concentrate on completing achievements and score hunting.
A game is first and foremost about fun, a long storyline is secondary to providing that experience. I love Halo but you wouldn't release Combat Evolved as a title these days as the campaign was too long, which meant it lost pace in the middle. Game developers like movie makers did are learning that its better to have more quality in a shorter amount of time to really make your story engaging. If a story takes too long to pan out then you lose your audience.







