I almost always write reviews (exceptions for books with many reviews already or some Aozora Advent works where I’m just busy and forgot) but I would love to review without star rating. Like @Biblio I dislike “rating” memoirs and I felt pretty icky about giving a star rating to a memoir covering child abuse, but I had to because I wanted to comment on it.
Also I see people writing about not knowing what to say in reviews. Please anything. I love reading reviews and I’ll take something over nothing!
I also love reading reviews of people hating books I loved because it’s fun to see how different people interpret the same book. The opposite is a bit less fun (but occasionally good) because people tend to be less specific when they like something.