Why do professors make students complete an annotated bibliography? To give students a hard time and task-master them to death?

No, of course not. It’s not just an assignment in and of itself; it is an important step in the research process. Your first stage was choosing a topic and doing some tentative research. Now you are going to find several relevant sources and provided a summary and evaluation of them. This is the topic you chose in Module 3, and this work will culminate in your final research project in Module 7.