Whilst I personally agree with you that it’s a good idea for an author to see both negative and positive feedback, I don’t see what’s the problem to allow the “criticism sensitive” types to protect themselves from criticism by toggling and option in their client which makes downvotes not visible to them (but it does nothing for others).

For clarity, my suggestion is not to allow people to disable downvotes, it’s to allow them to not see downvotes in their own client - downvotes are still there and everybody else who hasn’t “disabled downvote display” on their clients can still see them.

Think of it as a social interaction equivalent of installing ramps for people with disabilities on wheel chairs: nobody else is force to use the ramps but those who need them have them.