The beauty of the classroom water environment is that everyone is stepping down into the water. In the water students see each other face to face. The water provides a gentle hug (hydrostatic pressure) around the body and even serves as a misty blanket of sorts that makes it very hard for students to examine and see each other's bodies.
For some of us the thought of putting on a swimsuit to wear in a public environment can feel very uncomfortable. Being seen in this way may create a sense of feeling overly exposed. Unfortunately, media these days can aggravate a harmful and unhealthy view of our body image by the constant barrage of polished images that clash with the reality of what a real everyday human body looks like.
That being said, I like to tell students that there are many other options with water wear. The traditional swimsuit is not at all a requirement. I wear swim capris or swim shorts and a swim tankini top. I've seen students wear shorts and a t-shirt they don't mind getting wet. I have had students come wearing a burkini. The important thing is that you feel comfortable with what you wear and that the clothing allows you to move with your body in the water safely.