Using light weights in your workout can be beneficial for many reasons.
Please notice that I saidlight weights!
Unless you are planning to compete in body building events, there is no reason to load your joints past the therapeutic level of weight training.
Years ago, I worked as an aerobics instructor at the YMCA also and enjoyed workouts in the gym. It was painful to see so many people picking up weights that were way too heavy for them and watching their form deteriorate, which meant pain and injuries were inevitable.