It's already been a game changer in the restaurant world, where proprietors no longer have to price the cost of service into the menu. Sure, customers don't like it, but it does the job of price discrimination where it matters.
I submit that the US would not be able to maintain as dynamic a restaurant ecosystem as it has without tipping. Uber's business model is not sustainable with human drivers without tipping. Eventually drivers will leave once the VC money dries up and ridership declines due to price sensitivity.
Tipping is the safety valve that will allow ride markets to clear properly. Uber wanted a clean, easy user experience, right up until it becomes unsustainable. Now it is, and the only people who can keep the Uber service afloat is riders.