Costs US$199, most games are under $5. Goes with the kids in the car, in the bedroom, but still easy to confiscate and lock away.
Far better selection of educational games, not just twitch reflex shooters.
Serves double duty as a media player. Movies, music, Youtube.
Serves triple duty as an internet research / learning tool. How do volcanoes work? Look it up.
With Android 4.2 you can set up individual user accounts for each child & parent, so the whole family can use it. But it's still cheap enough that you can buy one for each person if you wanted.
Honestly, why would you get a console?