I understand that they want to protect their investment. Especially if the are selling the hardware at a loss (I don't know whether they are), but a bit more open mindedness could be so helpful in getting geeks excited (and maybe selling more consoles in the long run)
Look at the Wiimote. Did nintendo lose anything as the community began doing crazy stuff with it? I know of at least one case where the Wiimotes hacker-friendliness sold a console.