My guess is that Apple is trying to build channel momentum any way they can. Unable to pre-negotiate deals and launch with a huge splash, as they prefer, they're doing it from the bottom up, starting with content providers like Crackle that probably get a lot more out of it than Apple does.
But as we've seen, Crackle begets Smithsonian and Smithsonian begets PBS and PBS begets ABC. So it seems like it's working.
I bet in the next year, we'll see some sort of foldering option for home screen icons.
Actually, Apple has a relationship with the Walt Disney Company[1], which owns the ABC, ESPN and the Disney channels - and many more. Perhaps these additional TV apps were added after enough content creators agreed to whatever terms.
Also, interestingly enough, there is a show on Disney Junior that first premiered on the Disney Junior iPhone/iPad app before it was shown on the regular Disney Junior TV channel. Maybe this is a new model to beta test new content?
[1] http://en.wikipedia.org/wiki/The_Walt_Disney_Company#Disney_...
The bear case is actually the opposite - they aren't leaving any money on the table now, but it will be at the expense of future growth. They'd be better cutting over to stand-alone sooner, at a loss in current revenue, to better position themselves for the future. That may or may not be the right play, but that's really how you should be reading the current market.
Giant companies are often not very customer friendly, but they are rarely leaving obvious money on the table.
[Edited for clarity]