High minimum wage requirements could potentially end tipping. Imagine you are a restaurant owner in one of the cities with a high minimum wage. You want to get customers in the door, but you really had to raise your prices to pay for the minimum wage.
If you implemented a no tipping policy, you make the dining out experience more affordable for your customers. Yeah, the base price went up, but you don't have the add on at the end. And your servers are still making $15 an hour.
I would prefer it that the wait staff got a fair wage, assuming they received no tips. Then it could truly be "tips optional" with the tip only going to the person(s) you want it to.
What frosts me is when the restaurant adds in a 20% tip, which happens often with large groups, and they charge that tip on the tax! No way am I paying someone a tip for the amount I was taxed.