Doug,
For deer hunting in MI, there is a horizontal (East/West) line about half way up the Lower Peninsula, and South of that line is the "shotgun zone" (shotguns/muzzleloaders/pistols with straight walled cartridges .35 caliber or greater) only. North of that line is the "Rifle Zone" (Northern half of the Lower Peninsula and entire Upper Peninsula), open to center fire rifles and whatever is legal in the shotgun zone.
This line was designated several years ago (not sure when), before I started hunting in 1973. They used to allow .22 mags also, but changed that for good reason IMO. The line was drawn according to population density (people, not deer), and they have considered moving it further North, but nothing serious as far as I know.
I only live 3-1/2 miles South of the line, and hunt as close as 2 miles from it. I mostly hunt with muzzleloaders and a H&R/NEF Ultra Slug Hunter LE, but would hunt with a center fire rifle some (especially in pistol calibers) if it were legal.
I heard that Indiana is allowing center fire rifles chambered in "pistol calibers" this year. That will be a great way to start the younger guys and gals, with less recoil than the shotgun alternative.
So, the bottom line from here is "we have to by law".

Center fire rifles can be used in the entire state for predators and varmints.