Part of the problem in the northeast is the pros. Part is the cities which have so many other actvities. And part is that the old time powers-Army, Navy and the Ivy League, are pretty much irrelevant.
Even as late as the 60s, the Ivies still drew big crowds and got treated as major by the networks. But then the traditional programs of the region almost all became less significant.

Now in FBS beyond Army and Navy you have UConn, UMass and Buffalo, who are all recent move-ups. The only true northern "east coast" schools are Temple, Rutgers and BC, two of whom are historically bad. And only Penn St., Syracuse, Pitt and Maryland are also in the northeast.