I think the real motivation behind this design is more simple. Every time we see a lightsaber in a new game or movie, or even described in a book, they try to do something we haven't seen before to spark interest. It isn't about making a practical weapon... it's about catching the eye. I don't think this is practical, but all the speculation is free advertising. Darth mauls double bladed lightsaber is a perfect example, so is Count Dukoo's curved hilt saber. There are only three questions that matter... Does it look cool? Will you see the movie? Will you buy the toy?