Okay, the all 4 wheels thing is a good idea, but turning on rear only is a horrible idea. Here's why:

Let's ignore which end is front and which end is back. You've got a box. Two of the wheels swivel around, and the other two don't. Try pulling that box behind you, using only one hand, from the end with the fixed wheels. Thing goes all over the place, and you can't control it. Pull it from the end with the swivel wheels, and it just follows your hand.

Now push that box from the end with the swiveling wheels. You have to make huge movements to keep it going straight, and in order to make it go left, you gotta shove that sucker way over to the right. Pushing it from the end with the fixed wheels is much simpler. Push box left, box go left. Push box right, box go right. Much easier for meltybrain cave man to figure out.