Easy. They have less rolling resistance, ergo, have less parasitic losses and need less horsepower to move the car at the same speed. The question should be "is it worth the trade off?"
There is no more complex device on any vehicle than the tires. It controls braking, acceleration, ride, static and transient cornering, and noise.
And everybody wants to buy the cheapest piece of $%^ they can for their family, and then ignore them. Meh.