Such maps are even better than census records for showing the geographic relationships between residents. And those geographic relationships between families often led to family relationships between the children in those families. Lower resolution maps can be just as important in explaining the wider world in which your forefathers lived. These maps show larger areas at one time so you can see several states, or even several countries, at once. From this perspective some boundaries lose some of their significance, and you can see why families stayed in one place for years, or moved constantly.
History is perhaps the most important aspect of any map.
While the underlying physical landscape may remain constant for millenia, both the political landscape and the way an area is perceived can change, almost on an annual basis. As you consider a series of maps showing the changes in both political boundaries and mapping styles you can get a feel for your own progenitors' perspectives on the world around them. And that should be your purpose in using any map, ancient or modern, high resolution or low. They aren't just pretty pictures to glance at, locate a placename or two, and then discard. Take the time to study each map, not only for the specific towns or counties where your families lived, but for what the map can tell you about the time period in which it was made, and what its maker wanted to tell you about the area it covers.