As was pointed out in the comments section, it's not always great writing that creates a successful book.
Duh, Jessie. :-) Of course I know that. There's lots of books I've read where the writing was okay but it was the plot or characters that kept me turning the pages.
Welcome to the world of imagination. A good story will always have you turning the pages. But what defines a good story? Great writing? Vibrant characters? A fresh plot?
Ahhh, the land of subjectivity. It's a beautiful place.
Check out the comment section of my last post if you're interested in why a book might become a national bestseller.