And one of the results of this was that the PG-13 became the all-purpose rating. It also helped kill the notion of explicitly adult studio pictures outside of Oscar season and utterly crushed the notion of live action, PG-rated 'for kids only' studio releases. It, along with the likes of Spider-Man in 2002 and Pirates of the Caribbean: Curse of the Black Pearl in 2003, helped sell Hollywood on the idea of spending $150-$200m on an all-ages four-quadrant fantasy blockbuster that could make $600m-$1 billion worldwide as opposed to spending $90-$120m on an R-rated action movie and hoping for at best $350m worldwide. The first Peter Jackson Middle Earth movie, which is still a bloody masterpiece thank you much, was among the first modern (post 2001) four-quadrant, all-ages, all audience global fantasy blockbuster.
The Lord of the Rings: The Fellowship of the Ring came out in late 2001 and it (along with Harry Potter and the Sorcerer's Stone a month prior) basically kicked off what I like to call the 'all tentpoles, all the time' mentality in Hollywood.