true. any story has to have some basic things or it will never succeed. those books that were made into the movies usually were the type that did not require the movie watcher to think about it. in a few cases i know of, the movie verson took away what was required in the book. some authors can write for a viewing audiance and others cant. You did mention it being for money. most successful writers tell you to never write for money. there are a few exception. harlan ellison has frequently writen a book because he needed the money, but most of those were done under a fake name.
all the writers ive ever heard address the question all state that you write to express a story, if its good, it will make money, or at least get ppl to think. If its bad, you enjoyed writing it. I have actually writen three stories, but have never attepmted to get any one of them published. perhaps this one will be good enough i can.
