I'm not a movie person, but films like Home Alone, Back To The Future, Ghostbusters etc come to mind. My impression is that they are super hits that span generations because they are so predictable, middle of the road, easy to digest and unable to offend.
They were not predictable when released, which is partly why they became so popular. While none of them are ground breaking avant garde art, they all tweaked what was conventional, accepted and "predictable" in film making of the time. They became middle of the road partly because they helped to define the road.
I suppose we have a different understanding of predictability.
I find most block buster movies very predictable. The end is generally obvious (hint: the good guys win) and they follow a fairly common setup. That's not necessarily bad, you can produce very entertaining movies that way, and they're often very well produced and supreme in technical aspects, but they're not something I'd watch twice and usually not something I recommend to anyone.
They were mostly novel is setup and formulaic in progression. Just because the formula wasn't documented in as much detail as it has been since Save the Cat, both general storytelling and film-specific formulae existed and those films are logically consistent with them.
