I've ran into many providers where they had routers in the top 10 or 15 markets...  and that was it. If you wanted a connection in South Bend or Indianapolis or New Orleans or Ohio or...  you were backhauled potentially hundreds of miles to a nearby big market.

More smaller POPs reduces the tromboning.

More smaller POPs means that one POP's outage isn't as disastrous on the traffic rerouting around it.