^ Not really because the entertainment outlets have increased more than 20 fold. Your entertainment choices that consume your time and money are everywhere. The biggest factors are:
1) Home theatres - Better than the movies with nobody kicking your seat.
2) DVD's (Cheap) - Short window to DVD release and they're cheap.
3) Rentals - Babysitters are expensive...just wait for rental.
4) Pay Per View - Why even get up?
5) Piracy - Huge impact. You can go to LA right now and get X3 on DVD or download it online.
6) The Internet - Not only as a piracy tool but as a place to hang out for instance like here, myspace, etc...
7) Broadband Internet - Enabling fast internet surfacing, downloads, great for piracy, and it's just a fun place to hang out...and it's free.
8) Video Game systems - This isn't pong anymore. How many times have you picked up your X-Box or PS2 to play a game and 4 hours are gone in no time.
9) Online computer games/online gambling, etc...These suck your whole day away.
10) Satellite TV: You can watch all your favorite sports games without going out, tons of movie channels, etc...Not to mention the pirate cable and satellite boxes you can buy.
The population increase has prevented the #'s from dropping further than they have, but they have really really helped the international box office.
I don't know why there's even an argument here. It's like trying to say 8 track sales are down without talking about cassettes and DVD's. I would go to the movies way more often if it wasn't for all these other things to do. This has all been established as fact by all the media analysts. It's not debateable except for the % of impact.