As long as your passengers know the drill, it's not much of a problem. The sequence usually goes: Park, seatbelts off, driver opens door justa crack, rear passenger opens their door, gets out, closes the door, driver opens door, closes door. It does take a little bit more concentration to figure things out than it would a normal car, but I think it's worth it!
Since the back doors are so short, they don't have any trouble opening to full swing in a crowded parking lots. The main doors of the Element are also shorter than, say, an Impreza coupe's, so they're actually a little better for tight spots too. The doors "click" pretty solidly into positions between full close and full open, so you can bump them quite a bit on your way out and they won't move too much. It's just a shame that you can't open the rear hatch from the inside!