You can find all kinds of empirical data to back this up; I'll leave that to you. But what I've observed, at least anecdotally, is that while the way people consume advertising has changed, the way advertising is created, planned, bought and placed has not. Yet another version of that tired adage "Generals prepare to fight the last war." The same holds true for CDs, Executive Group Directors and CMOs.
If, as nearly everyone says, consumers are looking for experiences not just messages, an experience, except in the most Apple-ian of circumstances, is nearly impossible to deliver via a :30. You will never convince consumers to try Verizon's FIOs via a :30. You need something deeper.
Many ad people have bought into some of the above but not the totality. So they spend millions creating web "experiences" and some of them are quite good, but they spend $0 promoting those websites. In most cases, except of the last 45 frames of a :30, or a 6 pt. url in a print ad, there's no mention of their web experience at all.
What if we looked at the world differently. What if we said the :30 was the movie trailer and the website itself is the movie? That's the way I'm beginning to see the world. But as usual I am vox clamatix in deserto.