Never underestimate the power of Pokémon. The 3DS has been hackproof for over two and a half years, but give us a Pokémon game and suddenly you're giving people incentive to blow everything to pieces. And it took less than three weeks, too. For the time being we have the event Pokémon to show for it, but there should be more soon, like egg moves, whatever updated stats Serebii's list is still missing, and most importantly, whatever mega evolutions may still be hidden in the code (if there are any).
Well, I guess from Nintendo's point of view, it's a success... at least the games haven't been hacked to pieces before release. Of course, the leaking situation is another matter, but maybe the 3DS' successor will be able to last a whole month after its first Pokémon game?