There is the whole debate over which is better as far as reflecting heat(chrome) vs attracting and holding heat(black) and is it myth or fact. I remember reading an article about that back in the 80's as to why most camera manufacturers went to all black. It is purely a marketing ploy, and cheaper to make an all black unit, and label it a"professional" model. I believe this was due to the popularity of the Nikon F series, and not everybody could afford one, plus it gave the illusion your camera was just as good as the Nikon.
This is, of course, more ramblings from an old man, who's been around the block a time or three.