Big Ten teams are already making about 25 million from tv contracts. That will go up significantly if they can get the Big Ten Network on basic cable in NJ, NYC, Maryland, and D.C., which you would have to think the Big Ten knows it will or it wouldn't have added those two programs. The Big Ten also renegotiates in a few years, and by adding those markets will be in line for a much bigger payday.
This was solely a move about dollars, but at least the Big Ten is sticking with the whole education thing i.e both Maryland and Rutgers are in the AAU and are fine academic institutions.
I would also not be surprised at all if this opens the door for further movement (aside from Connecticut to the ACC).