I did respond to his points. Yet I haven't had answers from you for my questions. I've given many reasons why at least some of the roads don't make sense. And you've basically ignored every reason I've given without being willing to respond to them. So please don't try to tell me that I'm ignoring someone.
There needs to be a reason for how you do something on the map. It isn't something new here. I have reasons why these should not be marked. If there aren't reasons to refute those, then they shouldn't be marked. It isn't a demand, but a simple truth. If there is debate over whether something is correct, both sides need to provide valid reasons for their belief. You have yet to provide anything for the points I've made. Sketch made some points and I provided responses to his points. He is free to respond back. If you have any points, you are also free to make them. I haven't seen any yet other than pretty weak arguments such as that at the time when many highways were not marked, it wasn't very usable (I've explained that when all of the highways are marked, all major destinations from I-75 can be reached via the highway system) or that a road is *sometimes* faster (I've explained why a road doesn't have to be primary just for that reason alone) or that there weren't many on the map (there is no requirement for there to be any if they don't make sense). If you don't want to respond yourself to any of my many reasons, then that's fine. I'll continue discussing it with others. Besides, if they are so trivial to you, then you obviously don't have much of a reason for making the changes.
In any case, let's provide one other explanation. In the urban areas of southern Michigan, pick a point outside of a city on the map as a start point and another outside of a city as an end point. Assume there are no primary streets marked. How many routes can you find that seem logical if you don't know anything about the roads involved? Unless there is a highway that makes that be the only logical choice, you are likely to have many different logical routes to choose from. Streets are often very close together, sometimes as close as a city block even outside of the cities themselves. If you don't have any indication on the map for what is the best route, how do you know? The best route could be for any reason - wider road, faster speed limits, fewer stop lights or signs, etc. There may be half a dozen or even a dozen routes that would appear logical if you didn't have any differentiation in the streets other than highway or street. But there is likely at least one route that is far better because of those reasons. By marking it as a primary street, you provide someone with an indication of which route (or routes) out of many is the best.
Now, look at northern Michigan and do the same thing. Pick a start point outside of a town or city and pick an end point that is also outside of a town or city. Pick something that doesn't have a single highway route between them because that won't be a good example. Now, how many logical routes do you have? In most cases, there is only one or two routes that make much sense because there are far fewer roads and there is typically miles of distance between the roads that will get you where you want to go. You're not going to normally drive many miles out of your way if there is a straight route. In short, if there really isn't any confusion over the best route even if you don't know anything about the roads other than the layout and if they are highways or not, then there is no value to a primary street in that location. If there are a decent number of possible routes that are all logical if you don't know them and one of those really is better than the others (not equal), then that is where there is value in the primary street classification. In northern Michigan, there aren't many locations where that is the case and at least most of the ones provided are not that way.
Van Rd is marked as a primary from US-31. If you're at that starting point heading west, is there another alternative Street route that you might consider if you looked at the map and it wasn't marked as primary? Not really. You'd have to drive a fair distance to get to another street heading west from Van. Unless your destination is far enough north or south to where Van Rd is no longer logical (such as if you're going to Cross Village and then Levering is more logical), there really isn't an alternative that makes sense. So marking it doesn't provide any real value. And in reality, you may make someone think that Van to Pleasantview to Levering is as good as US-31 to Levering to get to Cross Village when it really isn't.