Just feeling the warmth of the sun on your skin is a delight, it's also delightful to be outside (even if perhaps in a shadow or half-shadow) and read something.
No, the assumption that it is universally delightful for people is an incorrect one. The heating caused by the sun on my skin is not enjoyable at all.
I would remain indoors forever if it were possible. I find being outside to be just as archaic as swimming in the middle of the open ocean; unnecessary and uncomfortable.
See https://pmc.ncbi.nlm.nih.gov/articles/PMC5129901/
Just feeling the warmth of the sun on your skin is a delight, it's also delightful to be outside (even if perhaps in a shadow or half-shadow) and read something.