Just because people buy more games doesn't mean that they spend more time playing games. I may want a trivia game and a sports game and a card game but I only need one camera program to take a photo. That doesn't mean that I spend more time playing games than taking photos.
Personally I think the photo, web and multimedia capabilities are the real killer app for smart phones, not games. I use the camera all the time for work just to record details or show damage of a product to a client. It's insanely fast and easy to just click share and have those photos ready in a web album on picasa. I also listen to podcasts, streaming music and talk radio all day from my phone.
I think you'll also find that even for those people who spend a lot of time gaming on their phones they probably buy a lot more games than they actually play. With so many free and discount offers on Android markets it's really easy to fall into a habit of collecting all these games even if you don't often play them. I know I do this even though I hardly ever game on my phone.