Like if you had the ability to utilize virtually unlimited storage space through just buying new large capcity external hard drives and were able to build up a huge library of material, then why would you need to buy pre-packaged movies/content nor use their $$$ on-demand service? No neither the content owners, nor cable companies would want to prevent you from having these choices.
Remember: artificial scarcity keeps prices high.
Why do you think the studios and cable providers fear to death all of the new channels avaliable to consumers for obtaining content? Their house of cards starts to cave in on itself. Competition is a very bad thing for these guys and they want nothing to do with it.