The more $$ you are willing to pay the better the dining will be. Royal Caribbean is considered a 3-4* cruise line, Radisson, Seabourn, Crystal, Silversea are all high end market, like the Four Seasons of cruising. Smaller ships. However Princess and some other lines including RCCL have specialty dining restaurants where you can get lobster at an added price, say, $25 per person.
On the 5* cruise lines you will be paying triple the price of RCCL. I can do without the crab legs to save $$.
From what I understand the cruises several years ago did offer high end seafood, but it's hard to turn a profit when you are serving 2000 people more expensive menu items.
Actually not just RCI and Princess offer alternative, specialty dining, so does Celebrity Carnival and NCL. NCL has the most choices especially on the newer ships. The price for these restaurants vary all over the place: Celebrity charges $30 per person, Carnival about $25 and this may or may not include Lobster and NCL from $15 up. There is usually an extra charge for Lobster.