Steve, I think you are right about the differences in subject matter. It always seems to me that in the 50's the colors were more basic, yet somehow more vivid or graphic. Now they look like a random scramble of uncoordinated crap. Just my opinion of course.
One thing Leiter does in a few photos that I could not find online is to make a photo that almost looks BW, but has just a few hints of color, usually a deep blue or something similar. It's a nice approach, I think.