When I only have an hour available, it's easier to just watch a TV episode on Netflix: it's hard to find an hour long movie. Even when I have an hour and a half, I still might choose to watch two episodes instead of searching for a movie that's only ninety minutes. And when it's one of those weekend days where I just want to crash for a while, well, it's easier to keep clicking the next episode than to watch a series of movies. Even on different days of the week, if I watch a movie almost every night, it can get exhausting to sift through so many stories--TV shows offer more fluidity.
With the rise of Netflix, along with Hulu and Amazon Instant and whatever else is out there, more people are watching TV shows online. And I wonder how much this correlates to our growing demand that shows offer an over-arching plot instead of just having individual plots for individual episodes.
If you're watching two or five episodes of a show in one day, or finishing an entire series in a month or two, it's hard not to have an over-arching plot. The show gets repetitive in a way that it wouldn't have if you'd been watching it on TV, one episode a week. We're starting to treat TV shows like movie franchises: we want each episode to be part of a plan. While watching a show on TV always leaves the risk that you might miss an episode and also an important part of the plot, if you're watching online that will never happen (well, not on Netflix, anyway).
The audience is shifting from once-a-week casual viewers to viewers who are investing a devoted, if sometimes short, amount of time to watching the show. That changes what the dynamics of the show need to become in order to suit this viewing style.