This is absolutely a no-brainer for municipalities. The private companies are charging a premium that they return to shareholders and give to executives. Municipalities have excellent access to credit at rates significantly lower than the premium charged by utility companies. The residents get cheaper access and more influence in how the utility is ran.
The number of people that pay for-profit companies for natural gas (heat), electricity, and water in North America is absolutely bonkers. There is a specific concern about foreign corporations purchasing water rights in the American west.