Like so many, I've bought a good zillion or so games on Steam. Of those, Triple Town is in my top five. (Don't shoot me for being in love with a casual game; Civ 5 is another one of those top five.) When I got an iPhone, I was really excited to get the game in portable format. But when I found out that unlocking unlimited turns could only be done as an in-app purchase, I sadly deleted the app.
Why, you ask? Because I have a US iTunes account on a phone registered with a†Japanese carrier. I can buy and download new apps, but IAPs are strictly off limits. I have a Japanese iTunes account, which I could use on the phone, but I already had a number of apps attached to the US account that I didn't want to buy a second time. Besides, most iOS games don't have language options, so if I were to buy games using my Japanese account I would have to play them in Japanese. I do play games in Japanese sometimes, don't get me wrong, but for the most part I prefer to play games in my native language.
Okay, you might say, but how many people are in my†situation? That's a good question, one to which I don't know how to answer. But if you consider other situations, you'll see that people all over the world have reasons to create accounts based in countries like the US. Up until this past October, the South African iTunes store didn't even†have†a games category. If you look at Apple support's†list of which countries' iTunes stores support which types of media, you'll see that no small number of countries is lacking certain types of content. It seems there are a lot of reasons someone in a foreign country might create a US iTunes account, and no one who does so can pay you for your work unless they can pay up front.
I have yet to submit anything to the iOS app store, so I don't know how much trouble/rigamarole is involved in getting an app up. Depending on the scope of your game and your intended audience, maybe it's not worth the trouble. I think it's worth considering, though, if it isn't going to be a lot of extra work.