Late response: There is some software I want to run that I do not have the source to. There is some software I want to run which is not being written because the person interested in writing it is not convinced that they will be able to distribute it to anyone in a convenient or profitable fashion.
I don't own a PlayStation, but of course have many other computers that are "appliances" (mp3 player, digital camera, etc.). I don't expect or even want all of those to be general purpose computers. For a long time I thought of my phone as an appliance, but with modern smartphones it's pretty clear that being a general purpose computer >> being an appliance and so I want to use platforms that are open in that way.