Another issue is market construction. Think about walking by a luxury goods store. Imagine you're on Michigan Avenue with the sky scrapers and the beautiful people, the August sun beating down and a light breeze to keep you cool. All those factors probably put you in a pretty damn good mood, the mood to spend.
Now imagine you're instead in downtown Detroit, browsing the same merchandise through poorly lit, grid-crossed holes in squat, cinderblock buildings. Maybe the goods inside are worth the same amount, but the average person in the same situation is not going to pay as much.
That's what the Android store is like. Two screenshots compressed at just insane levels like Google has run out of hard drives, and four hundred characters for a description. That puts anyone in the mood to spend, right?
A final factor is the miserable battery life of the average Android handset, which makes them less suited to be a gaming device if you want them to work as a phone later.
Also, how many games have really been ported directly to Android from iPhone? I mean good ones, now, ones people have actually bought on the iPhone. There's a halo effect involved too. If you go for years without seeing a decent game for a device, you end up being trained to think of it as a non-gaming device. On the other hand, I only have to browse the internet for a couple of minutes to find a half dozen iPhone games I wouldn't mind paying a buck to try out.