Why would Apple ever release a television?

Despite all of the analyst expectations and rumor-mongering from bloggers and other tech-watchers, why would Apple ever release a big-screen TV? What would be accomplished by releasing a full-fledged television that they couldn't already do with a box? The business is very low margin, and most screens above 50 inches sell at a slight loss, especially during the holidays.

Unless Apple could come up with a revolutionary technology from a display perspective which would allow them to mark-up the price substantially, I don't see how they could make any significant profit at all from the sector.

The real area where Apple could start another revolution would be in TV user-interface and software, where they could converge streaming services, iTunes, and a future App Store, on a more capable Apple TV box, where developers could write innovative apps with uses ranging from social media and video games.

It kind of reminds me of Apple's tagline for this year's WWDC: "Where a whole new world is developing."