Here's an interesting piece at the Escapist about the plight of gamers who have grown up and found they just don't have time to indulge in a 30-hour game with work, kids, spouses, and everything else demanding more and more of their attention. The author actually seeks out games with story modes lasting 8-10 hours, and that represents a month's game investment to him.
I'd take this a step further and advocate that more games be made intentionally shorter, but also cost less. Then, if the game does well, sell DLC or sequels to it. That way, once the game is 30 hours long it cost $65, but if I just wanted an 8-hour diversion, I can spend $30 on the basic game.