Quick Answer: James Cameron’s Titanic and Avatar are both incredibly successful, formulaic movies that reached the largest possible audience by not striving to be anything other than average. Cameron aimed for the middle with box-office friendly scripts that did not challenge or go over the heads of the typical moviegoer. On the technical level, however, Titanic and Avatar were far above average, offering showstopping spectacle to complement their safe, basic scripts.

In terms of worldwide box office receipts, Avatar (2009) and Titanic (1997) are the most successful movies of all time, grossing $2.8 billion and $2.2 billion in theatres, respectively. Yet the journey to complete each film in no way foretold the financial windfall that awaited it. At the time, both Titanic and Avatar were considered risky ventures, as they were extremely costly movies made from original concepts. Director James Cameron fought with the same studio (20th Century Fox) twice over each film’s budget, and his career was on the line during the production of both films. Due to Cameron’s persistence and certainty in his own vision, both movies became worldwide phenomena and financially successful beyond compare.

But what was the vision in which Cameron had such unshakeable faith? It was a vision of glossy, skilled mediocrity — unremarkable content in a highly remarkable package.

The reason why both films sold so many tickets is perfectly summed up by uber-popular website RedLetterMedia. Both Titanic and Avatar connected with the typical theater-goer because they didn’t strive to be anything other than “average.”

Of course, on a technical level, both Titanic and Avatar are far above average. Both films have transfixing cinematography and groundbreaking visual effects, which have left a mark on modern cinema. In their story-telling and screenplays, however, both films are formulaic. It’s no coincidence that both Titanic and Avatar were nominated for the Best Picture Academy Award (and Titanic won) but neither was nominated for Best Screenplay. Titanic and Avatar both have on-the-nose, sometimes cringe-worthy dialogue for which Cameron has become justifiably famous. Both films have one-dimensional characters and particularly villains: evil-doers such as Billy Zane as Kate Winslet’s pompous fiancé in Titanic and Stephen Lang as the redneck Colonel in Avatar. Leonardo DiCaprio as the dreamy Jack is basically a Mary Sue in Titanic — in addition to saving Winslet’s damsel in distress multiple times, he also proves to be adept at drawing and gambling. He is even well-versed in physics.

The basic narratives in both Avatar and Titanic have been criticized by many. Avatar has been dismissed as “Dances with Wolves in Space,” while Titanic can be summarized as “Romeo and Juliet on a Boat.” Still, in each case, the simple story appeared to help, not hurt, the film’s reception.

Yet the very thing that Cameron is most criticized for might be the biggest underlying reason behind each film’s success. It’s a methodology in keeping with lazy job interviewees the world over: “The funny thing about my greatest weakness is it’s actually my greatest strength.” Having a simple plot that audiences can relate to is hugely important for accessing the hearts — and wallets — of filmgoers. It’s why the newest Star Wars (2015), which capitalized on nostalgia and recycled plotlines, is an enormous hit, but complicated messes like the Thomas Pynchon-adapted Inherent Vice (2014), while critically acclaimed, aren’t financially successful.

Cameron’s ability to replicate his own success demonstrates (if it wasn’t already clear) that he knows and understands what he’s doing. While the themes of Avatar invite comparisons to Dances with Wolves (1990), Pocahontas (1995), and FernGully (1992), Avatar‘s narrative structure most recalls that of Titanic. Both films feature a love story in which boy meets girl a different world. (In Titanic, they come from high and low classes. Avatar, the interplanetary meet-cute is more literal.) The pair bickers at first, teaches each other new things and gradually falls in love. Then disaster strikes. Once said disaster draws to a close, the romance concludes in either heartbreaking tragedy or heartwarming happily ever after. Evidently, this story formula (plus dazzling visuals) is the key to making a lucrative blockbuster movie.

The reason why Titanic and Avatar were so popular is the same reason why people flock to Applebee’s. People like what’s average, safe and comfortable. And James Cameron will show you to your table.