I have to agree with epivosism about the TV experience. Waiting for the digital decoder to catch an I-frame slows down browsing immensely and it's just a lot less fun. Tivos are better, because they have multiple tuners and can scan the channels above/below the one you're on, which helps a lot. But it's still not as good as pushing the button on an analog tuner's remote and getting a new signal in < 1/15 of a second.
Maybe your comparison of live vs streaming TV is skewed because it takes so long to start a new stream that it's hard to imagine browsing content directly, instead of trying to imagine the content from movie posters.
Streaming video doesn't need to use I-frames for sync, there's a technique called intra refresh they can use to limit the error. That also helps with the nasty "pumping" artifacts you get on static images.
Some codecs do reorder frames for efficiency though (H.264 can be 10 frames out of order but realistically only goes up to 3), which means you have to decode a few before displaying the start frame.
Maybe your comparison of live vs streaming TV is skewed because it takes so long to start a new stream that it's hard to imagine browsing content directly, instead of trying to imagine the content from movie posters.