The reason they exist, we are told by those from marketing, is because all these type of second hand stories come with pre-awareness. That is, as an audience, we are already aware of the content of a story, of its style and genre.
As an example, we know a new 'Dukes of Hazzard' film won't be about 2 Spanish Dukes from a the regiment of Hazzard trying to influence the court to give back their land.
In other words the marketing is easy. No big plot explanations needed.
You can see how this works. And also why it annoys writers of new stories. Our thoughts go something along the lines of 'stop being so bloody lazy over there in marketing'.
However, be honest, there is a warmth in familiarity. We must understand that too. New things can be scary. Or else you wouldn't like these two examples of familiar things coming together in a new way. And you will like them. Its a Tim Clague guarantee!