[ ] It's vastly more powerful than what we had before.
[ ] The new features will allow us to explore new kinds of gameplay.
[ ] It's not easy to develop for, and any developer who merely ports an existing game will fail.
[ ] It will target a different audience from the last generation.
[ ] It may cost more to develop for, but it'll be worth it.
[ ] Our company is uniquely suited to develop an all new experience for this platform.
See this 3DS dev interview for example. They do the same thing every generation.