1) Increasingly exorbitant ticket prices.
2) Totally exorbitant concession prices.
3) Often subpar picture and sound quality.
4) Often uncomfortable seating.
5) Audiences that talk during films and don't bother to turn off or switch to "vibrate" mode on their cellphones and pagers.
6) The price of home theater systems taking a nosedive lately--including big flat-screen TV's and Blu-ray players.
7) The movies coming out on DVD/Blu-ray about 3-4 months after theatrical debut, often in the uncut original version that the director intended for the film.
8) The availability of video streaming services from NetFlix, Apple and Amazon--in some cases in resolutions as high as 1080p.
Small wonder not only do I watch a lot of movies on my 40" flat screen, but also am watching a lot of TV shows, too. Also, if you've seen the article from Fast Company magazine I mentioned in a post earlier, the arrival of the iPad and the cheap cost of e-book readers are also starting to hurt both TV and movie viewership, too.
You forgot the most important factor: loss in quality of the average movie, as well as the increasingly anti-Christian, Anti-American, and pro anything weird, or progressive “plot”s.