I have no problem with the "auto-tip" on Princess and HAL nor do we have a problem on Regent (an all inclusive) where the tips are "included". If we receive exceptional service we usually add a little. I find we tend to do that more on Regent since the passenger to crew ratio is so much better you get a lot closer to those serving you.
I knew an officer on Princess once who had worked for more than one line, he quit, but before he did he told me pretty much the entire industry treats those making up the greater contingent of the crew as "slave labors". I agree, but then the counter argument is that many of the crew make a lot more on these ships than they ever could at home, consequently are able to support their families back home in a relatively elevated life style.
I have seen a lot of my fellow passengers really treat the crew nice, tips and otherwise. However, I have witnessed some of their actions that makes me ashamed of being part of the human race.
On a lighter note: John Maxtone Graham has written a number of books on ocean travel and cruising. When he was young his family traveled a lot between Britain and New York so he got some exposure to the days of the North Atlantic first class and steerage travel. He has great anecdotes. He was a guest speaker on the original Royal Princess years ago and titled his presentations after his book "The Only Way to Cross" he told a humorous story that goes something like this about tipping in the old days (It was customary to tip waiters, room stewards, etc. on the final morning of the voyage):
"On a Royal Viking ship some years ago, a perennial complainer carped ceaselessly about his food-the steak was too rare--the mashed potato too lumpy and time and again the coffee too cold. On the last morning he demanded a hotter cup of coffee. When the steward, anxious to please, raced back from the galley, he found"--- his guest gone, having jumped ship without leaving a single cent. Years later, when working in a New York City restaurant, as a waiter, the steward spotted this same individual dining there. The steward rushed into the kitchen, got a hot pot of coffee, ran out and gave it to the guy apologizing for being so tardy with his coffee.