yea, because the user base is so big or users find out about the app and then start bugging the developers to death( example - Temple Run, Instagram, Angry birds etc ).
Rovio didn't want angry birds to be *FREE* on android, but nobody was buying the app, even after it was popular on IOS, so they released it for free and made revenue through Ads.
Temple Run developers stated they kept getting emails asking when will the game be available for Android , so they outsourced somebody to port the game over and now 80-90% of the emails they get are problems with Android. and when they ask users what device and OS version they are running alot of the times they get something along the lines of " I'm on custom rom x" and they wonder why its not working. the podcast is on touch arcade.
The fact is, developers are pressured into programming for Android because the userbase is so big. I can tell you from personal experience, we spend 2x the time on our android app then we do our IOS version.
Survey: 'Ice Cream Sandwich' can't stop Android fragmentation | Application development - InfoWorld