Why are they so interesting? in general they aren’t. They are interesting to you and that’s what matters.
I’m not going to get into a debate on the merits of Austin because there’s no point and all I want to do is touch on why some people love an item while others can hate it.
Why you find it interesting? Right now your experience, desires, knowledge base, interests and a few other factors lineup with what the book presents in it’s text therefore you find it appealing.
If they do not line up then you do not find it appealing.
Variations between the general factors and the “bits of you” will cause different levels of enjoyment in different individuals. Sometimes say a shift in your knowledge base will wreck something you previously enjoyed.
As your life changes things become more and less appealing that’s life.
Basically right now you are in the same headspace where the author was when she was writing so you connect to it so enjoy it.
Yes, it’s common.
They can be released at the same time to cash in but the script always comes first.
The Phantom menace received such a treatment. They take the script and have an author rewrite it as a novel. In the case of the phantom menace it was the fantasy author Terry Brooks.