The real story here is not the UDID ban which we knew was coming (and is easily counter-able as demonstrated in the comments already), but the forced iPhone 5 support.
Now this wouldn't be an issue except that Apple doesn't allow you to support the iPhone 5 without targeting iOS 4.3 or higher. So this kills off support for iOS 3.1.3-4.2. This might not seem like such a bad thing, but if you're targeting certain demographics like kids (as I am), it cuts off a significant percentage (7% in my case) of users.
Now this wouldn't be an issue except that Apple doesn't allow you to support the iPhone 5 without targeting iOS 4.3 or higher. So this kills off support for iOS 3.1.3-4.2. This might not seem like such a bad thing, but if you're targeting certain demographics like kids (as I am), it cuts off a significant percentage (7% in my case) of users.