The only reason? What about all the games and apps that don't come to Android?
Yeah, that's a great reason to go with an iPhone. But this is the enthusiast approach. The guy who's got a budget set aside for games. You and me.
My understanding is that the norm picks a certain low-two-digit number of apps to buy when they get the phone, then buy the occasional procrastination / usability app every quarter or so.
You will be satisfied with an Android device if that's what you want to get out of apps.
So here's a realistic example: You have the 30-something guy with a flat in a city, a car and an underpaid fulltime desk job. He's in a relationship.
Chances are this guy will be happy with what the Android Market offers. He's already got GPS covered, he's got Google Maps, Twitter and FB, the basics are pretty much dealt with out-of-the-box. He's maybe gonna pick a radio listing/streaming app, 5 low-attention-span games (of which 4 are probably free), 2-5 apps related to his secret hobby and 3 apps related to productivity (on the level of Evernote).
If he's in an appropriate country, he's also gonna pick up to 3 video streaming apps, provided he's got WiFi (most people do).
And he's gonna get an app for his favorite 2 magazines / newspapers / whatever.
Finally, he's gonna pick up to 6 procrastination apps (chug beer, make fart noises, that kind of thing).
That's already a lot of apps for this guy, or anyone. All of this is on the Android Market.
If you have basic needs that should be covered by an app, you're gonna find what you need on both infrastructures. When you're an enthusiast of some kind, your chances of finding app after app relevant to your interests on the App Store are higher, and the median quality of those apps is going to be higher; same for the price. Like, if you're a gamer, you're gonna drown on iOS devices, and you would probably want to because choice is good and you've got your sources to pick the best stuff.