Lawsuits and the threat of lawsuits can have a significant positive effect. First there are the obvious ones like Brown v. Board of Education. Then there are the not so obvious ones.
Let's say you're a businessman in a company that makes widgets. There is a change you can make to the widget process that saves money, but is dangerous to the consumer. Without the threat of a class action lawsuit that would be tempting. With the threat, there's a very real chance someone's going to sue the pants off of your company for that decision.