Doug what you describe as Number 1 is now Number 10, etc. No change in the routing, just flipping the nines.
As I understand it, When the course was first completed, the nines were as they are now -- Number 1 was/is a Par 5 along State Street, and Number 18 was the great finish across the pond. All of that routing, I think, was geared toward the finishing hole.
But for a long time in the 60's - 90's, the nines were reversed. And while it may just be my own sense of familiarity with that rotation, I thought it was the superior setup. The desire may simply to have been to have a first tee that was in sight of the windows from the clubhouse, I don't know. But old habits and old familiarities die hard.
By the way, my favorite bit of trivia about the Michigan Course is that it was the site of the first USGA Junior, in 1948, and a teenager from California named Ken Venturi was the runner-up, losing to Dean Lind of Rockford, Illinois in the final match.
(I asked Jack Nicklaus once about the Michigan course, and said to him that there is some story about him doing such-and-such on just about every hole on the course, and he said, "I honestly don't remember the course at all.")