I also hate the assumption that I want to tip. If I ran a restaurant, I would prefer to know if a customer wasn't 100% happy.
'We hope you enjoyed your meal and would like to leave a tip, if not please let us know where we went wrong today, we'd love to get it right next time!"
I would also want to know that my customers were happy - I hate the way big companies proudly trumpet a 90% 'would recommend to a friend' rating as a huge positive, rather than wondering/caring why they've seriously disappointed one in every ten of their customers.
To be honest, I would clearly add to the menu something like "We aim to give you excellent service as standard! We pride ourselves on paying our staff a very fair, realistic living wage, without having to rely on tips, and the prices we charge for our food and drinks are all-inclusive - therefore, the price on your bill is the price we ask you to pay, and not a penny more." Then, I'd have a charity box at the bar/till for anybody who doesn't get it and insists that they want to overpay for what they've had.
Additional service charges are a con (even if claimed as optional, but you then have the faff and awkwardness of rejecting them): I used the toilet in Asda yesterday, borrowed one of their trollies and scan machines, it was nice and warm and light as I shopped and all the goods I wanted had already been put on shelves ready for me to take.... yet for all this, they still only charged me the total price of the goods I chose to buy, as shown clearly on the shelves. I can only assume that they set their prices based on all of their costs in supplying the goods being covered - an honest and straightforward thing to do.