[potatolicious]

It's more than the economics of owning a studio - Sony's ownership of their studios actively harms their other, actually profitable, product categories.

Look at the PSN's movie rental store - perpetually hamstrung by limited selection. Why would competing studios want to get into bed with one of their biggest competitors on their closed service?

Similarly, it creates internal conflicts of interest. Sony's electronics are constantly crippled when it comes to content, probably at the pressure of owning their own content themselves. For the longest time it was impossible to get any movies on a memory stick, forcing PSP users to buy them on expensive and battery-murdering discs instead. It took years to fix that mistake, but of course, by the time they did, public interest in mobile movies had basically all but disappeared.