While I totally agree that some games just take far too much of a commitment in terms of time to play through (like starting to play a new MMO) Mass Effect 2 is a pretty bad example. Ok I did spend pretty much the entire weekend after I bought it pretty much doing nothing but sleeping, eating and playing it so that I'd done everything (i.e- main story, all loyalties, side quests, 100% exploration, actually listening to the conversations, talking to party members, the free DLC) there was to do in about 25 hours. But that wasn't in any way necessary.
Playing through it again now at a much more sedate pace (in real world terms) it's very easy to split up into 20 minute chunks while I am waiting for something else or taking a break from working on something. If anything it's kinda scary just how quickly it is taking this time where it looks like being around 10 hours to finish just the main plot (though admittedly the difficulty level affects the time it takes enormously after having a go at insanity with my first shepard again and seeming to have twice as many opponents to kill and only about half as many bullets as I would like).
At the end of the day if the game was any shorter than it currently is I'd start expecting a significant discount in terms of price, as yes it's hellishly good fun, but actually over pretty quickly.