Ernest Hemingway did not describe his characters, and his fame never suffered for it. So do looks matter, and should you or shouldn't you include them in your books?
Let's Get Physical
Anne Shirley has red hair. It's an important part of her book series, and something everyone knows about her. In this case, hair is a big part off the story. But I've read many others where the looks of the main character didn't much matter...and they were included anyway.
I tend to be partial to characters who have blonde hair, like me. But is that a positive or negative thing for the authors? What about all the books out there about brown-haired girls? If I have no description to go on, I'll imagine a character who looks however I want them to look. That allows me as a reader to see what I want.
But you as the author may want me to see what you want, and that's when looks do matter. A clear description of a character also helps you with branding (always important). After all, what would Harry Potter be without his glasses?
It's your story to tell, so you decide whether or not you need to add physical descriptions.