iPhone 4 Won't Support Turn-by-Turn Navigation

From http://www.apple.com/ios/ios6/maps/

"Some features may not be available in all countries or all areas. Flyover and turn-by-turn navigation will be available only on iPhone 4S and iPad 2 or later. Cellular data charges may apply."

How is this okay? Even my iPhone 3G ran several third-party turn-by-turn applications - albeit fairly poorly - and my iPhone 4 ran them without any problem. What is the possible justification for limiting this feature other than to force users to upgrade hardware?

I don't mean to come across as an Apple hater, but iPhone owners have been waiting for this feature for years. I was surprised when iOS4 didn't have it, much less iOS5. Now it's finally coming in iOS6, but only if you have the most recent iPhone hardware?

It just doesn't seem right.