To me, cruise ship luxury is seamless service, terrific food, high crew to guest ratio, well-designed cabins with great amenities, and, yes, inclusive of gratuities, spirits and unexpected extras such as Seabourn's caviar in the surf.
You also compared Marina to Crystal. I do not.
The only extra-fee dining is Silversea's very special wine pairing dinner. There are NOT "many luxury lines charging extra".
Marina is a new ship, part of Oceania Cruises. There is no comparison between Oceania and Seabourn or, indeed, Crystal.
Paul, you do not seem to understand loyalty of Seabourn repeaters. Please cease criticizing Seabourn until you have sailed on her.