DRM and TC can be used in useful ways, again it is not the technology, it is the use of the technology that can be good or bad.
What are these useful ways one can use DRM and TC? The whole point of TC and DRM is after all to prohibit a user from updating their software, or from listining to their favourite song on their music player of choice. I cannot see anything useful about these things. Encryption doesn't even come into the picture, since you can do TC/DRM without encryption; I think this is what Tivio did, they just signed their binaries, and the hardware only allows running binaries signed by that entity.