By leaving it open to interpretation by the cabin crew as to which side to jump from would seem to me to be a bit of a cheap effort.
I don't think that in most cases it is possible to specify a side to evacuate from. The cabin crew are (should) be trained to evaluate the state of the exit and the area outside before using it. Engine fire on left engine?, are all the left exits unusable? almost certainly not on a big aircraft and how can you tell from the flightdeck. Don't tie their hands by rendering half the exits out of action before you start, quite possible a slide on the other side will not deploy leaving even less exits to use. I know the certification is done using half the exits but in reality you need every one you can get.