Earlier quoted context omitted.
I sincerely hope not. If you bought a book but were told you could get an extra chapter of storyline added in for extra money, you'd wonder "Does it contribute to the story in any way?" Ultimately, no. Or "will the story make sense if I do not buy this extra chapter?". Hopefully yes; hopefully the story makes sense without this extra chapter. I wouldn't want to watch a film with extra fluff that added nothing to the…
I hope not either. But this is a popular model in videogames, and it somehow both pissess off players and earns the studios tons of money. You obviously can't apply it to every movie, but you could appply it to quite a few. For instance, there's little point in extra content for Inception, because the movie world is defined by the start and the end of that very movie, and as you said, it has to make sense in its basi…
I think this could totally work for something like Inception too. The film has a backstory suggests at a wider context beyond what's shown in the scenes. Most stories do. That's why fanfiction exists.