I think the 70s disaster films are the backbone of many of today's blockbusters. Glad you sighted Titanic. People tend to think of it as a Romance, but really at its heart, it's a disaster film. One of the reasons I think the genre is so effective, is that the heroic sacrifice in the face of danger is built into the plot. In The Towering Inferno, Steve McQueen was offered the lead role of the architect that built the building (the role that ultimately went to Paul Newman). He declined. Instead, he wanted the role of the lead fireman. I think this choice illustrates how prevalent heroic sacrifice is to the disaster genre. He chose the character that runs into the burning building to save those trapped in it. Look at how many characters in INDEPENDENCE DAY directly risk their lives to save the planet. Will Smith (at least twice), Jeff Goldblum, Randy Quaid. Character is conflict. And nothing is a better platform for conflict (and thus character) than when things go to shit.