Nobody purposely sets out to make a lousy movie. Unfortunately, Hollywood prizes concepts over execution. In other words, Hollywood prefers a good idea over great writing. Ideally you want both a good idea and great writing, but given a choice, Hollywood chooses a good idea every time.
While this might seem cynical, it’s actually logical. If you write a great script about Russian medieval poets in the 16th century, it doesn’t matter how great the story might be. The topic alone will drive audiences away. That’s why great writing is less important than a good idea.
On the other hand, if you come up with a good idea, that alone can grab an audience’s attention. Then Hollywood hopes that executing that great idea can be done well (which isn’t always the case).
So the first step in writing a screenplay is testing your story idea on others. If the people find that story idea intriguing, then the second step is to focus on the writing.
However if other people don’t find your story idea interesting or appealing, even the best writing in the world will have a hard time getting anyone’s attention. So focus on your story idea first and your writing second. A great idea executed poorly can be fixed with multiple rewrites (hopefully). A mediocre idea executed perfectly will still struggle to attract an audience.
“Booksmart” was an idea floating around in development for years before finally being turned into a movie. The idea was appealing: two smart teenagers realize they spent all their time studying and missed out on the fun of being in high school. So they plan to party and make up for their last four years in a single night.
Whether you liked “Booksmart” or not, the idea is still interesting, which is why the actual story got changed around but the main idea still remained the same. Would the original script have been better than the modified one that was ultimately shot? Who knows? But we do know that if Hollywood didn’t like the idea of “Booksmart” in the first place, it’s chances of getting made into a movie would have been close to zero.