Well Uber serves a few important tasks: they make sure that quality is okay. Obviously its not perfect, but really bad offenders can't hide, but will be baned quickly. Compare that to taxis, where in some cities you couldn't be sure whether you'd be robbed or raped when taking a ride. Uber solves this problem, at least mostly.
Yes, they are the evil middlemen, but they aren't much different from McDonalds or other franchise model companies. Even CocaCola does this:
So if many well established companies have been doing this for decades and centuries, then why not Uber?