Your system is better. But it's special. Special is bad because I don't like having to do things X different ways for X different restaraunts. I would rather pay a little more and not have to remember the quarks of your restaurant. I am also just trained to tip so I will feel icky leaving your restaurant no matter if you are paying them a fair amount already.

So if you charge more money to include the tip I will still feel obliged to tip anyway and I will leave with the experience your restaurant is too expensive and not come back. In short I think you've done the right thing. Don't fight the mob, embrace it.