Oh, I agree that it shouldn't matter, but obviously Rovio wasn't interested in spending the effort on developing iCloud sync specifically for iOS (and perhaps eventually Mac OS).
I know quite a few people that have both an iOS device and an Android device. I have a Nexus 7 and a iPhone 4. Very soon I could have an iPhone 5 and an iPad or i might keep the Nexus 7 and get an Nexus 4 or HTC One. It is nice to have the choice if you need it.