Of course, as CNET notes, it's about the money (isn't it always?). If studios can make more money from the TV networks than they can from online rentals, then obviously they're going to go with television. The only problem with that, however, is that with an exclusive agreement, they'll never know, will they?
And of course the other issue here is the actual definition of places like iTunes and Netflix -- obviously, retail stores aren't barred from carrying these movies, so does that mean that Netflix and iTunes are actually content channels rather than retailers? Tough issue. You have to think that it'll eventually be settled in favor of digital distribution (what consumer wouldn't want to watch a movie on their own time rather than sticking to a TV network's schedule), but until studios are convinced otherwise, exclusivity agreements will likely be the rule.
[via Apple Insider]