Well for one clothing. I know some feel that they want pants or a less robed SW with a double bladed lightsabers. Another could be the new build have different moves for lightsaber choices. This could be pertained to guilds who RP and really want their character in game. For example before release their was a person in guild who's character looked more like a SI but duel wielded. So they had to make a decision on whether to go SI or SW. This is just how I feel. Again I know complete customization is probably impossible but I would like something that is pretty close.
edit: Also if you guys are going to say that then their is no need for classes then your wrong becuase BW said their all about story so even though you can get both types of lightsabers you should play for the different story lines.