I don't think it's untoward to wonder why a young, fit woman is having serious surgery, when she is a future head of state (or spouse of one). It's rather shocking and very newsworthy. Chastising people for being interested is ridiculous; the entire raison d'etre of the royal family is to maintain public interest.
With Covid on the rise and other germs about, most physicians would rather get patients out of the hospital as soon as possible. I hope she recovers quickly and is able to recuperate at home.