Cruise lines such as Royal Caribbean are trying to attract more Gen-X and millennial vacationers, and in doing so they sometimes come up with crazy, over-the-top ideas -- think: robotic bartenders, simulated sky-diving, and shipboard amusement park rides. Some are successful, others not so much.

Royal Caribbean scored a big hit with the robots, but the line's attempt to "revolutionize" cruise ship dining was... not so much.

"Dynamic Dining" probably sounded good on paper. The idea was to get rid of main dining rooms, and instead passengers would come onboard and, just as in Vegas or Paris, choose where to dine each night -- making a reservation at one of 18 themed restaurants (some free, others for a fee). The concept was introduced on Quantum-class ships, including the New York-based Anthem of the Seas, and officials were so sure it would work there were plans to bring Dynamic Dining to other ships.

But what sounded simple wasn't. More than 4,000 passengers ended up trying to figure out where to have dinner, only some of whom had bothered to make reservations in advance, and many shut out of their top choices.

Royal's repeat passengers especially didn't like it. They are used to a more traditional My-Time Dining scheme, where you're assigned a time, a table, and a place for dinner, or you can opt to dine in an open-seating dining room (when not splurging on for-a-fee specialty restaurants or going casual at the buffet).

Last year, the line made some tweaks but it still didn't work. As of November 27, Dynamic Dining will be no more.

"Royal Caribbean International prides itself on pushing the boundaries of innovation and constantly creating amenities and experiences that exceed the expectations of our guests," the line said in a statement this week. "Our guests have told us that they prefer the ease of a cruise vacation where they have flexibility without having to plan extensively."

Translation: What cruisers want is a no-brainer.