Love this! Pay people what they are worth.
I have mixed emotions about tipping. That's the single biggest advantage of the tipping system is that people get paid what they are worth, no more, and no less, by the people most qualified to judge the quality of their service, their customers. People who are best at service get paid more, and people who are worse get paid less.
The biggest negative to the tipping system is that it has become an obligation, not a discretion. Most people tip a fixed percentage, never more, and never less. At that point, it loses all purpose, and people get paid the same regardless of how good they are. Myself, I have always varied my tip depending on the quality of service. I've been known to tip very little for bad service, and I've gone as high as 150% for outstanding service.
Again, I have no strong feeling about the tipping system, because I think it has ceased to be effective. I have to wonder how people who oppose tipping feel about pay differential, however. In other sales jobs, people are paid on commission, so better sales people may make substantially more than others. How would people feel if one waitress/waiter who was merely adequate earned $9/hour, and another one in the same restaurant who was more outgoing earned $15? Fair? Not fair?