Maybe if it was public these diseases wouldn't be so stigmatized. It might have a social impact now, but I see that as the issue.

I don't think it should be up to someone else what I am allowed to be embarrassed about, or what I want to keep private.

I don't think changing society to not be embarrassed about things being made public is a good solution to privacy concerns.

Also, we might have a million, non-embarrassment reasons to want to keep things private. I might not want people to know about my cancer because I want to be able to live my life without having to answer questions about it, or have people treat me as delicate. I might not want people to know I am pregnant because I don't want to have to tell them when I have a miscarriage.

Most importantly, I want to be able to have whatever arbitrary reasons I want to keep things private.

I think you're underestimating people's ability or inclination to abuse information for personal gain.