I'm not sure about the semantics/philosophy of it being a preference, but it is something that makes me deeply uncomfortable.

I recently started seeing a new doctor for my blood tests, and all of the staff were very polite and sensitive, they did everything "right". But when my obviously cis doctor introduced herself with "my preferred pronouns are she and her", I felt incredibly patronized and othered by it.

I've been living as a (binary-identifying) woman for a third of my life now, and, as far as I'm aware, nobody knows that I'm trans unless I've told them. I know how cis people interact with each other, and "preferred pronouns" are simply not a part of their experience. When my doctor goes to see her doctor, or her lawyer, or whatever, she doesn't declare her "preferred pronouns" to them. She declared them to me, because I'm trans (or at least because I was going to a clinic for trans people, but that's kind of the same thing).

I feel like this kind of interaction only emphasizes the fact that I'm trans, which is the exact opposite of what someone should do if they want to make me feel comfortable. I don't want cis people to switch into some stupid code language whenever they're around me, I just wanted to be treated like a normal person.

I get that they frequently have to interact with non-passing trans people, genderqueer people, and others whose pronouns/identities might not be immediately obvious, and maybe that's the best way to deal with those situations -- but I'm not non-passing or genderqueer so I can't say. I also get that the "preferred pronouns" thing has been pushed (and maybe was invented?) by actual trans people -- although I think when I see that advice come up on this site it is usually in the context of a someone who has just come out, not any generic interaction with any trans person. But anyway, that's how I feel about it.