So, question: if a Jedi really wanted to, say, kill a stormtrooper, could he or she just snap the trooper's neck with the force? Or pop his heart, or tear out the stormtrooper's eyes? It seems that they would be able to, since the force does not need line of sight, and the jedi are pretty accurate with it, but if so, why would they ever use a lightsaber?

I've seen this question answered a number of ways, but I don't want to assume anything.