Typing in all lowercase makes you look more vulnerable, it's a pretty common rhetorical tactic in PR.

I had never noticed this before. Can you point at any examples?

I have long noticed high profile people going to court with some kind of cast on, though.

I heard that altman does it. I don't care about him enough to check though. More silly gimmicks like holmes talking in a mans voice or jobs wearing the same turtle neck

Agree, it makes it seem like the individual is "one of us" and that what they're saying is a little more raw/genuine.

"They're being mean to me." vs "theyre being mean to me".

Uh, no, it makes you look careless and unprofessional.

How it's perceived is no doubt in the eye of the beholder. I can totally see how some people would associate this writing style with children, and so associate it with "vulnerable".