Yeah, I always try to make that argument and no one listens to me. I've been told in the past that if they offered a better way, or charged less for games then not so much pirating would go on.Â
In my honest opinion though, they could sell the games for 15-20 a piece and people would still download them. And as you've stated, I don't see being able to play the games before you buy working either. People will play and go "Oh man, this is sweet. I'm totally downloading this"
Obviously there's no way to stop piracy but I believe if nintendo reduced the price of their games and had some sort of demo system they would see less of their games copied.
One of the reasons I pirate is because the games are so expensive. If they lowered the price I would buy more games and I'm sure many other people would too.