I do believe that the populist movement helped to change society. It did not create much change right away, but it did do so in the long run. It changed society by helping to bring about the Progressive movement, which did a lot to take power away from the business elites of the United States and to give it to the middle classes.
The populists wanted the government to help the lower classes. In particular, it wanted the government to help farmers. It felt that the government was constantly on the side of big businesses that were hurting the farmers. Therefore, it wanted more government regulation of those businesses.
The populists did not get what they wanted. However, their ideas lived on and, in a couple of decades, were taken up again by the Progressives. The Progressives were middle class people who wanted to reduce the power of business. They championed many of the same causes as the populists. The Progressives, however, were much more successful. They were able to get the government to start doing more things to help the people.
I would say, then, that the populists changed society in the long run. They helped take away much of the power that big business had over the government. Because of the populists’ ideas, government gradually moved towards greater democracy and away from being corrupted and “owned” by the business elites. The government started to do more to help regular people and less to help big businesses. This is the long-term legacy of the populist movement.