Benefits of not using the streets... City boundaries rarely follow streets, so you can have large sections that have no streets around them that are part of a city and you can have odd shaped edges on cities. By not using the streets, the boundaries can be "drawn" to match the real boundaries. This can be useful for a number of reasons. For one, the boundaries are accurate. By being accurate, if you were to add a new street while the city layer is turned on, you can easily see if the street is inside or outside of the city boundaries (or half in/half out) so you can set the city name correctly. Unlike with using the streets, you won't have times when a street that has the city name assigned doesn't appear within the boundaries due to the way the polygon is shaped. Sometimes, the automatic polygon can cut off sections of streets as it tries to best cover the area.
Benefits of using streets... For one, this is currently the only way to edit the city layer ourselves and only works for cities that aren't on the actual city layer. And second, there isn't any extra work that needs to be done beyond setting the city names on the segments correctly, which is already needed. You don't have to go another step to change the city layer directly. So it can be a little less work. And second, in cases where the boundaries may not be known, but where you know at least the main roads that are inside the city limits, the automatic polygons can help to highlight the city fairly well. If you were trying to add that to the city layer, you'd have to guess the shape and position of the polygon and that's somewhat less ideal.
In the end, we need to be able to get access to the city layer itself and remove the automatic city polygons that are based on the streets. Once we can edit the city layer, those won't be necessary because we can just add them in ourselves. And then we have a single layer to worry about. That being said, I think the potential of having multiple layers could be useful - a city layer that works like it does now, a mailing/address layer that is used for searching for addresses to help with address problems, and even township and county layers that can also be used for address searches. For other countries, you might have other things that can go into layers to help with searching. But from the client or Live Map, you should only see the city layer. The rest would only be available through the editor and used for searching. Just my opinion on that, though.
As far as townships, almost all townships in Michigan are currently just the name without Twp or Township, so any that are being kept need to be fixed. North of Roscommon (and probably even further south), I can't think of any townships that need to stay in either the lower peninsula or upper peninsula. I think the townships that are actually used are all down south around the larger cities. I may be wrong about that, so anyone can correct me if there are townships that are important in the northern part of the state that I'm not thinking of. I can say for certain that McKinley Township can go, having lived within that township for around 15 years. And having lived there and traveled around the state, I can't think of any others up there that are really necessary.
I probably mentioned these in the other thread, but here are ones that are actual problems rather than just annoyances...
- Bliss [township] - First, it isn't needed. Second, unless it's removed or changed to Bliss Twp/Township, I can't highlight the town of Bliss on the map.
- Conway [township] - There is a Conway Twp in southern Michigan and a town of Conway in northern Michigan. Unless Conway township is removed or renamed, I can't add Conway to the map without calling it something else such as including the county in the name, which I'd rather not do.
- Carp Lake - I am unaware of a Carp Lake township, but apparently Carp Lake is somewhere on the map because I can't add it to the map. So wherever that is, we need to find out if it is legitimate and what to do with it.
I know I also included some cities in that other thread that just need updated because the city layer doesn't show the boundaries even though the streets are correctly marked. I won't include those here, but you'll want to take note of them if you're going to bring these to Waze for removal/fixing.