A layover is a movie trailer for a city
A layover in a new city is like a trailer for a movie. The plane swirls and tilts over the city, and you see it from all different angles. You get a feel for the place before you have even stepped out of the airport.
I link that view with maps. After the flight I open the map, trace where the plane flew, and look at the river, the coast, the roads, and the parts that looked interesting from above. That tells me whether I want to visit the city in the future. If the answer is yes, I add it to my list, and later I plan a trip around it.
It is the same reason trailers exist. You get a feel for a movie while watching one, so they show you ads for other movies. A layover gives you that feel for a city, even if you never leave the airport.