Since my main use of screenshots is usually to illustrate something I saw, or offer How-Tos, I'd be irritated at screen elements that randomly did not appear far more often than ones that always appear.
My point? Only that it doesn't really matter what choice Apple makes, someone is going to think they blew it.
And yes, in the past I have blown a fuse trying to document something that doesn't show in the screenshot. I don't remember exactly what it was, but it was something that only showed for a few seconds before fading. I couldn't take the screenshot fast enough.