"But ultimately the movie industry isn't about the price you can gouge for the seats, but the number of bums that fill them."
It's both. I wouldn't have minded watching PotC4, but there was no way that I was going to fork out £10 for a 2D ticket or £14 for a 3D one. The *quality* of the movie is what determines it's worth, not what the cinema charges for it. Avatar was, rightly or wrongly, touted as an excellent cinema experience, which was why it was popular and sold lots of 3D tickets. PotC4 was certainly an also-ran and obviously not worth (to the punter) the mark-up that Vue, Cineworld et al. wanted to charge for 3D.
When it's only a 6 month wait, and especially when money's tight, people are far more willing to wait for Amazon (cheap), Lovefilm (cheaper) or TPB (free!) to have it available instead of spending ~£50 on a family night at the cinema. Even for a couple, it's cheaper to buy the BD than take the missus out for the evening.
Hollywood, like the music biz, need to focus on product to shore up their dwindling sales. The public want *decent* stories played out with *good* actors, rather than bad vehicles (Your Highness) or shoddy remakes (Arthur). 3D should only be used when there's a real case for it, otherwise it's just a distraction from the story.
Biting the hand that feeds IT
