They were most definitely not taken for athletics. They were taken for their market assets and alumni location (as was Maryland, but they at least have some basketball and football tradition). They do the job they were intended for: provide exposure in the NYC corridor, give the many Big10 alumni a game to go to every other year (many PSU, UM, OSU and Indiana alumni in the NYC area) and be in a great football recruiting area. Football will be a tough go in the Big10 East with four very good teams.
As far as being horrrible in sports, each division has to have teams at the bottom. As far as a doormat goes, you can't get much better than being the flagship school in a state of 9 million people in the largest market in the US. Yes, I would prefer a UConn over Rutgers, but I don't get to make that call and I understand why the Big10 did.