Should writers care if their book rating is below a 5 in a 5/5 rating?

 No.

Never.

Does Every book you read merit five stars? Few that I read: do. I read a great deal and being old now have read thousands of books. I would rate, perhaps, thirty or fifty of those; five stars.

Five stars is the ultimate accolade. I never pretend to myself that any of my books are worth five stars though I am heartily glad when they receive them.

I never trust a book that has five star review after five star review. Every reader is different, Some will enjoy my books some will hate them, some will never read them. That is the way the world works. Lol- how many people love the works of Jane Austen? Millions. I found them trite and silly. One star from me. Even the very best of authors have those that dislike; a story, a tale, a way of telling, an imagining, a character, a happening, a theme, the genre. Few five star reviews are genuine unless the book is truly exceptional. Few books are.