Tipping is not a city in China...

Or so I've been told. However, that is not the issue today. My issue
is with restaurants that instill a mandatory tip for larger groups which
seems to imply any group larger than 6 or 8 depending on the
restaurant. I just don't understand this practice. My issues are as
follows:
1. First and foremost, tips are OPTIONAL. They are to show
appreciation for good or exceptional service, and the amount is in
direct relation to the level of service.
2. I don't think any group stiffs the waitstaff unless the service was
extremely. In the rare chance you get a group that does not tip, that's
the price you pay, and refer back to issue #1.
3. I usually tip much better than their "required" tip, however if I am
forced to tip, I will only tip the amount they are demanding rather than
the larger amount that I probably would have left. Have I let
restaurants know this? Yes I have.

And yes, I have worked as a waitress in the past, and no, I never felt
tips should be mandatory. I was always grateful for whatever I got, and
always tried to give the best service possible with the old fashioned
smile and politeness. I think I must have done a good job as my tips
were pretty good. This is the purpose of a tip.

How do you feel about this practice?