Naturally, that makes the game a desirable product. And we all know pirates like to steal products, rather than pay for them. If you're one of those pirates, reading this post, then you should probably be informed that piracy hurts game developers. In the case of Pixeljunk Monsters Deluxe, it's hurting a lot.
So much in fact, Q-Games' Dylan Cuthbert (genius behind the Pixeljunk franchise) was prompted to Tweet about the issue. "I don't think we'll port anything else to the PSP, we have to see how PJMD does as there's a lot of piracy."
Cuthbert did later clarify to Joystiq that it will very much depend on the actual sales of Pixeljunk Monsters Deluxe as to whether PSP ports occur in the future.
So dirty pirates, if you're reading, support developers - pay for the games you intend to play. Otherwise we might end up with no games at all. You're not only going to harm us legitimate consumers, but also the industry and ultimately yourselves.