While that definitely would prevent piracy, they won't do that. That would mean you'd have to connect to the internet the first time you use a game, and that would be stupid. Like when I got Smash Bros 3DS, I was playing it before I even got home. And suppose you for whatever reason can't connect your 3DS to the internet or something, then you wouldn't be able to play any games. It seems that Nintendo doesn't think that everyone with a 3DS has internet, since they don't like to use internet features much or require them at all. And some people don't use their 3DS at home but only during travel and such, that would be quite a burden to them if they forget to register their game or something and can't use it.