I would be all for a set service charge. I never understand why people like tipping. Restaurants should be just like every other business. Charge a set price and it is up to the customer to decide if the price is worth it.
If you eat at a restaurant with a mandatory service charge and service was lousy? Just do what you would do in any other business situation. Complain to a manager/higher up and/or take your business elsewhere. I never understood the idea of how much you pay being based on how satisfied you are with the service. Naturally in the US when eating at restaurants I am a flat tipper, I am also looking forward to my trip to Ireland and the UK in a few weeks. Taxes and service included. Price you see on the menu is the price you pay.