If I remember correctly, on a CRJ you are supposed to throw out the window exit. It will fit through the opening if you turn it sideways. On a large plane that would be hard due to its weight, but on the mouse-sized CRJ it's probably five pounds.

If that is the case, it makes sense to me. The exit row on a CRJ looks just like all the others -- crammed. There is no place to keep it in the cabin. Besides, once you get through the exit (this only works if your waist size is less than 36"), you're only a few inches from the ground. Who cares if a little door is in the way.