If they added just a few BIG things it would change the face of the game.
Open world pvp objectives. Put the WAR back into STARWARS. Let the players build up player bases that could even function as a fleet hub. Give the opposing faction the ability to lay siege to it and knock it down (or take it). However, to do this properly they would have to limit how many people on each side that could be in the zone. Force 100 vs 100 or 200 vs 200.
Semi-limited space. Give people the ability to fly around. Maybe add in a mini game or possibly another crafting/gathering profession to coincide with it. Give players the ability to visit battleships (if they can find them) and do quests there. Maybe even add a few noninhabited planets with resources you can't find anywhere else. They really could do just about anything and win.
Add 2 new classes and 2 new races. Add a social class like Musician, and a combat class like some sort of demolitions guy or combat musician (like a bard). I want to be able to play the blue guys that look like elephants. Make it so!
Then the normal stuff they always add. a few operations, flashpoints, hard modes, world bosses, etc.