We've had some other threads about this same topic here, and it's not against Let's Encrypt's policies for hosting providers and integrators to charge for Let's Encrypt certificates or for obtaining them, but it is, as @griffin said, disappointing when HTTPS isn't already a built-in feature for every hosting plan.
(I guess you could think of it as like a restaurant that chooses to charge for tap water?)
You can also check this huge thread with information about hosting providers who do support Let's Encrypt automatically, normally at no additional charge: