I haven't seen anyone mention it yet, but a reason might be that providing an API is cheaper than web scraping.
If people really want access to your data, they can just scrape your website, but that requires loading all the data through the website itself which requires loading millions or billions of video thumbnails, comments, descriptions, recommendations, etc. It's much cheaper for them to send a JSON through an API, even though they might know that some people are trying to undermine them by using that data to circumvent their advertising.
#1 IMO is that they don't make anything original anymore. I don't want to go see a live action remake of a classic cartoon movie. They can't possibly recapture what made the original great, and to be honest, what made the original great was probably the ignorance of youth and the nostalgia filter through which you personally view it.
If movie theaters are doing poorly, the movie industry should try to make smaller budget and slightly riskier original movies and movie theaters should charge less for a seat if they're having trouble filling cinemas. They make most of their money from concessions anyway and those are optional, so just get butts in seats and you'll make more money.