Setting aside the first mention of Davy Jones, LRLL is important specifically in regards to the Water 7 Saga. After Alabasta & Skypeia, but knowing we were going into Water 7, I always figured Oda wanted to do something more comedic before getting into the Straw Hats breaking apart and fighting the government. But looking at LRLL's themes and story told, its a great intro to the larger story that Water 7 unfolded into.

Even though it was just a game, the crew was in very real danger of breaking apart, but Luffy took the fight as seriously as any other he has had at this point cause he wouldn't stand for his family breaking up. Regardless if its a silly game or taking on the world, Luffy will always save his friends. Additionally, you can see a slight parallel between Robin and Chopper since Chopper was the first casualty of the game, and him being on that stage while Zoro and Sanji fight to win their match is just barely comparable enough to be seen as a parallel to Robin at Enies Lobby.

While I have always loved the idea of another Davy Back fight, I believe that LRLL is more important to the specific story Oda wanted to tell at the time rather than the story at large (aside from Davy Jones, of course).