Why use lightsabers in Star Wars?

Because it is a symbol of honor, those who can use it are those who have strong control over the Force. Only those who pass the test of jedi order can own a lightsaber of their own. This kind of thing is obviously popular in movies, as if anyone can use a lightsaber. Look at the people who use lightsabers, the most powerful Jedi and Sith warriors in the universe!