My only real issue with the new policy is for the buffet restaurants. I don't feel that an 18% tip is proper for the entirely self-service buffet places like Chef Mickey's, Boma, etc.
Although they're not exactly the most definitive sources, to reference two sources of info:
The website
www.tipping.org says for "Buffet-Style Restaurants" the tip should be 5-10%. Personally, I usually go more along the lines of 10-15%
http://www.tipping.org/tips/buffet.html
My sister, who has been a waitress or bartender at least part-time for most of her adult life, told me $2, in reference to the Golden Corral buffet place in her town. I don't know the exact price of the buffet there, but it's about $15-20, making that a 10-15% tip.
Of course, at places where it's All-You-Can-Eat but it's *not* serve-yourself, such as the family-style meals at Ohana, Garden Grill, etc, the servers should be tipped as a regular full-service restaurant. They do just as much running around (and sometimes even more-so) as your regular sit-down restaurant.
Apart from thinking twice about going to the buffet places with the DDE discount, I'm perfectly fine with an automatic 18% tip, as long as management can reduce it if we do have truly bad service. In those instances, I'd probably want to speak to the manager anyway.
-Rob