Laws against public nudity are more the law following the society than the other way around. Hippie girls got "topfreedom" passed around here yet women still don't walk around topless despite it being legal because it's heavily stigmatized. It's not the law that keeps our clothes on as much as the society.
Christianity, especially the varients that made their way throughout the anglosphere is rather prudish around nudity which had a huge influence on peoples attitudes.
Looking aside from why things got like this, laws against nudity are generally nice. Do you want to accidentally bump into somebodies nude body walking downtown? I don't think so. You want to swim at a public pool and have somebodies dick slap against your face? I don't think so.
There is an argument that nudity in specific contexts like sunbathing and sauna makes sense and I agree with this.