1) make your first revision barebones with no features whatsoever, making it so competitive in price it will most likely be successful (nintendo realized the 2DS should have been the original 3DS, when they announced it)
2) get game developers on your side, grow a library
3) now with your established brand on the market, make a revision adding in features that were needed since day one
4) force people to buy it by making revision-exclusive games for it
5) in the long run, it's actually much more expensive than purchasing a single feature-rich system once if you consider buying 2 models of the 3DS compared to, say, the vita
This has the potential to become a new pattern in the console process. Why sell a system only once, if people are willing to buy it several times over the course of a generation under the threat of "hardware revision exclusives"? "System exclusives" are not worthy enough hostages anymore, it seems.
A similar case happened with the DSi too, right? Except the DSi came too late when nobody cared about it/had no time to establish itself, I guess they are adjusting their shot at forcing people to buy several systems per generation.
Boy, modern nintendo sure has been walking the modern capcom route.
Something worth noting: the vita suddenly became much cheaper than the 3DS, as existing customers won't have to own a second system to play all the compatible games. Guess I'm done using this argument in the favor of the 3DS now.