I serve at a restaurant in Disney world. At least with serving and in most cases tipping is essential for us to make a living. @jeffjagoe most of the time a included tip, is just a suggested tip. A tip can be completely removed or if you liked the servicec you can increase the tip to compensate appropriately. Not only is the hourly wage for most servers next to nothing, but in most resturaunts especially major corporate ones the server is expected to "tip-out" anywhere from 3 to 6% of their sales. At my particular place of business it is 4%. A percentage of that tip out goes to the bar, hostess, and busers. This is a part of a bigger problem where these corporate places are using the servers to pay the labor for other positions in the restaurant. All these other positions being tipped out rely on the servers sales for their income as well. Also if a no tip is left at all for the server they still pay out of pocket to serve the table. Serving tables is like being a 1099 contractor, we pay for all our own supplies and equipment( shoes, uniform, office supplies, etc.) and essentially are just leasing the space or "station" we have in a restaurant. The food the ambiance and theme is the product we represent and sell.
Tipping is very IMPORTANT. I am not saying all service deserves one cause sometimes someone really sucks at their job but it is essential part of our income for servers and the other service support staff.