Who would buy a new phone just for voice nav when they can download it?
Ok. Granted.
That said, I remember my extreme annoyance when I had an iPhone 4, and there was no Google Maps app for it, and Apple in their wonderful wisdom decided not to enable voice navigation in their new Apple Maps app for iPhone 4 owners, for no reason other than to create an artificial limitation to encourage upgrades. A move that still annoys me to the point where I take the opportunity to mention it when I get the chance.