Tom
A really interesting question. In my experience, there are individual holes (if not courses) that produce a feeling of "expansive privacy" and others that produce a feeling of "focused privacy" -- and, in the holes/courses I'm thinking of, the difference is a function of routing and (more so) site character.
There's a replica course that I've played, on a good-sized site. When I got to the hole based on the 18th at TOC for the first time, I'd never experienced anything like it. The fairway was so wide, the sense of space and freedom so appealing, I was absolutely hooked. The horizon opened up on all sides, and you couldn't see another soul. That was a feeling of "expansive privacy".
On another course I've played, which has 27 holes on a smaller site with many mature trees, and which was laid out by the owner-amatuer designer in the 1950s, the opening holes of two of the 9s are side by side, and pretty close together. It can be a pretty busy course, but luckily -- from my perspective -- the trees between each hole are tall enough and packed in closely enough that you can still get a sense of privacy, but in this case it is more "focused privacy".
I do have a preference for the first kind over the second, but I enjoy both, which is a good thing because if I want to play golf I'll be experiencing both anyway.
One of the other interesting things about this question is the "historical perspective". What I mean is, it is a question that's relevant today, but was it one that occured at all to the earlier designers/players? Pine Valley aside, when I see some early pictures of some classic courses that are NOW tree lined, you see that they were originally much more open (with saplings or small trees here and there, but certainly not "tree-lined fairways).
The answer to the following question I assume is very "course-specific", but do you think the designers at the time thought of this issue? Did they intend that their courses would eventually have a feeling of "focused privacy," but only when the trees matured? Did they/could they take the long view like that?
Peter