Ever wonder which questions students are getting wrong over and over again? Sure you can grade your quizzes by hand and count everything out or you can just have your students take the quiz online and instantly get a report. Moodle and perhaps other LMSs lets you see a breakdown of all the questions.
How does this make your teaching better? Well for one, you may have writtena bad questions which isn't very fair to your students. For two, at least you know what your students don't know. All of this instantaneously.