Nintendo is being naive if they think this is going to help alleviate piracy issues. People who want to pirate games will find a way to pirate games, whether the equipment to do so is out in the open or not. The R4 cart is also not the only means for people to download games -- we're sure Nintendo knows this.
All the same, we can sympathize with Nintendo. The fight against piracy is an uphill one, at best, and since there's not much that Nintendo can do about it, they're doing what they can.