Bradley,
Given the large roles both CBM and HJW played in the birth of golf and gca in Chicago and America, I think it would be a mistake to underestimate them as prominent Chicago designers. They were there and quite productive in the beginning and in my mind that counts for a lot.
As for Watson, I am envious that you got to see a course where is work is still somewhat intact. He did quite a lot of work in California, but with changes it is a bit difficult to tell what is him and what is someone else. I don't know if it is accurate or not, but I've read that he was known for building quite large greens . . . do the greens at Kalamazoo fit this mold? I'd love to see photos if you ever get the chance. Even that old photo of Belvedere at that link is fascinating. Some here have tried in the past to dismiss Watson as a dark ages designer but, while his bunkers were apparently quite deep and difficult, from what I can tell his work was quite impressive.