I find both ratings and comments valuable in helping me determine if what I write entertains readers. If I divide the number of folks who rate a story by the number of downloads, it is almost consistently 1% - regardless of the rating itself. One of my stories reached 2%. I thank you all who vote - it is appreciated.
On the other hand, I am astounded at the stories with hundreds, even thousands of downloads with the symbol that indicates not enough readers have voted in order for the story to be rated (as opposed to those authors who have ratings turned off).
Folks, it only takes a couple of clicks, and it means a lot to us who write, and actually to you readers - because it helps us determine what and how to write.