I think the biggest confusion about that 70s-80s transition is that the films were more glitzy than gritty, and those sort of low-budget made-in-the-streets films were made in less quantities and by less superstar directors.

Really, the notion of the 80s being the birth of high-concept is wrong, because you can apply that to a lot of the 70s films too. "Three guys hunting a shark," "a bunch of people survive an earthquake", "a girl is possessed by the devil" "a bunch of kids in a small town drive around on graduation night."

And the notion of blockbusters being born in the 80s is inaccurate too. The 70s was full of star-studded disaster movies in the first half of the decade, and fantasy epics in the second half. Airport, Earthquake, Poseidon Adventure, Airport 77, King Kong, Jaws, Superman, Star Wars, Alien, even The Exorcist which had an enormous budget. And then you had the films that had blockbuster business, if not in content, like Godfather. The transition into the early 80s is pretty seamless.

I think the biggest difference, and what gives us that 80s=commercialism feeling is the merchandising. It began with pop soundtracks, like Top Gun, and then you had video game tie-ins, cartoon shows, toys, stickers and stuff. That started in the 70s too, but other than Star Wars it was relatively few except for the odd Earthquake lunchbox or poster or stuff like that. It finally pushed the high-concept, big-budget blockbusters that you had in the 70s into new areas of commercialism, and that laid the business strategy groundwork for todays films. Especially since the movies were in generally more slick-looking, and there weren't many made-in-the-streets films, it highlights this aspect even more.