Console Hacking

Several news outlets are reporting that the PS3 has been compromised. What strikes me as odd is that most of the time, the people doing the hacking have no interest in piracy (at least, that's their claim). Instead, their motives seem to be towards allowing home-brew app creation. This is a noble goal, and one that will surely become more and more popular, as we start moving away from passive entertainment towards a more participatory model.

My question is this: Why do console manufacturers still struggle to prevent home-brew projects? The time spent trying to prevent these sorts of exploits must be incredible, and so far, none of them have succeeded.

Personally, I'd love a console that allowed me to run whatever code I want on it - imagine the uses! MythTV running on an XBox? Awesome!