I saw the movie in 1997 at The Casino Theatre on Santa Catalina Island, and I would have much preferred a more accurate, documentary style of telling the TITANIC story - WITHOUT the gratuitous drama of Rose and Jack.
However, that story-within-a-story did point out something quite fascinating about life, which (as I see it) is that our passion for money can suck the meaning out of our lives. So, Jack took Rose to the wonderful party in steerage, and she saw maybe for the first time how much fun life can be, how 'real.'
But that is a whole different story, and it should have been told separately. TITANIC would have been better without it.