Mostly seen in commercials, what is the point of showing the speaker of the commercial in profile? Who is s/he talking to? The wall? What’s the point?
I believe the conceit is to simulate as if s/he were providing an interview/presentation to a 3rd-person interviewer/audience (thus sometimes it’s not in profile but in 3/4 angle), and we’re “looking in”, rather than directly delivering us a pitch. One plus to this is that the subject need not be trying to pretend to make sincere eye contact with the camera (us). One minus to this is that some people still want that.
I think JRDelirious has it right. I remember noticing this in some commercials by a brokerage (I forget who the ads were for, but they starred Sam Waterston). My impression was that they were trying to show that they provide objective advice and multiple perspectives.