While I can't say what would happen on many cruise lines if tips were included in the fare, I can say that this system has produced outstanding service on Radisson. My friends who have cruised Seabourn and Silversea say it is the same there (perhaps even a bit better on Seabourn). And, there has been no real trend for tipping to start up again. Once on a cruise out of Nice, France, our luggage was delayed by the airlines till the next day. Our room Stewardess brought us a bottle of wine and glasses, invited us to sit on the balcony in the provided robes for an hour or so while she had all the clothes we were wearing washed and cleaned.(all gratis). When she came back with our clean clothes, I broke the usual Radisson procedure and offered her a tip, because this service was above and beyond usual room stewardess duties. She politely declined!
One reason some of us feel we get inferior service on land overseas is that the US is probably the fastest-paced society in the world. In England (for example) the service was really fine but a bit slower than I am used to here. But then again, the entire pace of life was slower there!