Humans love convenience. Anybody who spends ten hours a week in traffic will jump at the chance to own a self-driving car.
As for the coordination issue: we can reduce traffic by increasing the level of coordination on the roads. Much of those gains can be achieved through self-driving cars. More gains can be achieved through self-driving cars with high-speed communication among vehicles. Eventually, we will reach the point in which any additional gains would require a central control system. Each step has its pros and cons.