all of this is 100% true, hence why the "content is king" myth proves to be untrue. However, what changes is the delivery, the technology, the themes, the context, the cultural aspects and so on.
For example, a guy fucking a somehow chubby (for nowadays standards) girl with natural body hair was the norm until mid 80s. Now we call it "niche". Another example: a few years ago many programs outdid the competition by having... HD content. It didn't matter if it was good or bad content as long as it was HD. Then the same with mobile. Maybe we'll see the same with 3D.
In short, content doesn't matter much, what matters is perception of added value. An off-adult example: Twitter. The lack of content by definition. If someone told you 20 years ago that people would be connected to a computer telling they ate a sandwich and a network of people would "retweet" that... what do you think you would have said about that? Probably a joke, or the people telling that was crazy, or a liar. Now it's the norm, the standard. The form, the added value, the cultural context over the absolute absence of content, meaning or depth.
Anyway, for those interested in the subject, just take a look to the pretty long but hopefully informative
article I wrote some time ago