Indeed. When I was studying photography formally, there was an unspoken assumption that students should compose in the camera and print "full frame." That's one of the reasons why artsy student B&W photos often have the messy black border -- it's to prove that the image was composed in the camera, not the darkroom. Some people see it as a bit of a poser aesthetic, but I have to admit I kind of like it.

Here's an example that I think I've show around here before:

It is interesting to note that this aesthetic is hardly ever applied to color photography (which is considered by artsy hipsters to be intrinsically less "artsy").

As Amanda points out, Weston used a view camera, which involves a lot of patient setting up and composting, so it is natural that you wouldn't crop later unless you wanted to present the image in a different aspect ratio or something. But when shooting quickly, it's a different thing. I find I frequently crop when I'm using digital, partly because I don't have a lot of faith in the viewfinder or screen's fidelity as it relates to the final image. Also, I frequently present digital images in aspect ratios very different from what the camera recorded (which involves chopping off some stuff).