I think there are just too many games now. We have a choice of thousands to play from and more are released daily than at any other time in history.
Is this necessary a good thing though?
Nintendo don't have a track record of releasing a glut of games every year. They can wait many years before releasing a sequel and perhaps it is that artificial scarcity that make some of their games more cherished. You know it will be a long time before you will play anything similar so you will feel compelled to play a current game for longer than you would possibly have done if a new sequel is due next year.
All of us are saying the same things about our playing habits. We frequently play a handful of games for a very long time and have a list of games with very few hours sunk into them. So why is that?
Is it that we are buying them on impulse and just not enjoying them? Are other games just so much better and take all of our time?
Change in buying habits has had a large impact, think about the amount of sales, bundles and key sites and you can understand why many people have dozens and dozens of games in their library.
I remember mega drive and playstation days where I would be paying 50-60quid a pop and would make damn sure I played the hell out of them even if they were duds! These days if I've purchased a bad game it's either refund on Steam or just move on.