By Mark Savage
Entertainment reporter, BBC News
In the not-so-distant past, every summer blockbuster had to have its own chartbusting theme song.
Batman: The Dark Knight is the latest song-free blockbuster
Bryan Adams did everything he did for Robin Hood; Whitney Houston would always love her Bodyguard; Celine Dion's heart, she assured us, would go on, despite the sinking of the Titanic.
But, musicals like Mamma Mia! aside, recent blockbusters have been bereft of big-name ballads. From X-Men to Pirates of the Caribbean, there isn't a power chord in sight.
Most striking of all is the complete absence of rock music in the rebooted Batman franchise.
Hans Zimmer, who co-wrote the soundtrack for Batman Begins and The Dark Knight, says his vision of Gotham City has no room for the likes of U2, Prince and R Kelly.
"There was never any doubt that we were going to be songless," says the Oscar-winning composer.
"And, trust me, we were flooded with requests from every band in the world. I actually had to say no to some really interesting people."
UK'S BEST-SELLING MOVIE THEMES
John Travolta and Olivia Newton-John - You're the One that I Want (1.98m sales)
Wet Wet Wet - Love is All Around (1.79m)
Stevie Wonder - I Just Called To Say I Love You (1.78m)
Bryan Adams - Everything I Do (I Do It For You) (1.55m)
John Travolta and Olivia Newton-John - Summer Nights (1.52m)
Whitney Houston - I Will Always Love You (1.36m)
Celine Dion - My Heart Will Go On (1.35m) pictured
Coolio - Gangsta's Paradise (1.25m)
Art Garfunkel - Bright Eyes (1.16m)
Zimmer's decision, taken in collaboration with director Chris Nolan and co-composer James Newton-Howard, reflects a sea-change in the way film-makers approach soundtracks.
Even when a top 40 artist gets involved, they work in conjunction with the composer to create a song that is part of the fabric of the movie.
Take, for example, Annie Lennox's Oscar-winning Into the West, which runs over the closing credits to Lord of the Rings: Return of the King.
Co-written with the trilogy's orchestral composer, Howard Shore, it was conceived as an Elvish lament for those who have sailed across the Sundering Sea.
Hardly top 40 material, then, but it complemented the film perfectly.
Narnia composer Harry Gregson-Williams says he prefers to work in this way - and recently collaborated with quirky New Yorker Regina Spektor for the theme song to Prince Caspian.
"We always wanted a song for the end credits but there was no question of there ever being a song in the body of the film," he says.
"Regina came and spent two and a half weeks with me to make sure that the song felt like it belonged to this film.
"I think it's a very pleasurable way to go."
Gregson-Williams has experience of films being gatecrashed by towering rock songs, having worked on apocalyptic asteroid adventure Armageddon, which was dominated by Aerosmith's I Don't Want To Miss a Thing.
Gregson-Williams credits include Shrek, Bridget Jones and Armageddon
He says those sorts of bombastic anthems "have been left in the '90s" but notes that the last couple of years have seen the emergence of a new type of song-driven soundtrack.
A prime example is 2004 indie comedy Garden State, which was underscored by a collection of achingly hip indie tracks from the likes of Remy Zero, Coldplay and The Shins.
'Ton of money'
The album was compiled as a labour of love by director and star Zach Braff - better known as Scrubs' goofy Dr John Dorian.
It shifted an eye-opening 1.2 million copies in the US, and set a new trend in soundtracks, particularly on offbeat comedies such as Juno and Little Miss Sunshine.
Alexandra Patsavas, music supervisor on TV shows including The OC and Grey's Anatomy plus several Hollywood films, says the pick-and-mix approach serves directors better than shoehorning in a famous name.
"The song has to support the drama," she says. "So I'm less focused on the big blockbuster than making sure every song fits."
Another advantage of using off-the-peg material by lesser-known bands is that it's cost efficient.
Spider-Man 3 bucked the trend with an original soundtrack album
"Artists want a ton of money now," Kathy Nelson, president of film music for Universal Pictures, told Billboard magazine.
"I remember the days when I would spend $300,000 (£151,000) for a soundtrack like Pulp Fiction and I thought the cost would put the label under. Now artists want $300,000 just to show up."
The producers of Spider-man 3 came up against this very problem when they decided to create an old-school blockbuster soundtrack last year.
"It cost a lot of money," admits Jordin Tappis, president of Record Collection Music, who compiled the album, and enlisted the help of Irish rockers Snow Patrol to record the film's big hit, Signal Fire.
"Snow Patrol are signed to Polydor in the UK and Interscope in America," he explains. "Our label at the time went through Warner Bros records, and Sony Pictures has its own music division.
"So there were three giant, major media conglomerates fighting for a percentage of a pie.
"We had to split the profits of each sale. Nobody made a tonne of money, but everyone did well enough to make it a successful endeavour."
Tappis believes the financial woes of the music business are largely responsible for the fall-off in big movie themes.
"When album sales were at their peak you had a pretty good chance that, if the film did well and the song connected, you could sell a lot of copies," he says.
"Nowadays, you're not selling as many records and the album becomes a souvenir. People aren't willing to take the upfront risk as much as they used to."
But maybe there's a more pragmatic reason for shutting pop out of the cinema.
"However big a genius Prince is, I do think it was a mistake shoving all those Prince songs into the first Batman film," says Zimmer.
"I remember thinking at the time, 'Oooh, this is going to bite them' and, yes, those songs really date the movie."