@TheFaithfullyDeparted: There are so few things in life that can't wait 90 minutes for a response. If it's anything truly important, they can call and you can exit to take the call. 99% of the texts you receive aren't emergencies that can't wait for an hour and a half, but you still have to check your phone. That's a disturbance to everyone else, and it may be a minor one for you, but it adds up when several people do it. Honestly, kudos to whatever theatre you were in for ensuring that everyone else wasn't disturbed by your texting. Your text may or may not have been important, but theatres can't start judging the importance of texts. Your text is just as annoying as anyone elses, no matter the subject.
Naturally, I don't think you're the real issue in most cases, unless you get important texts at every damn screening you go to :P The issue lies with the people who will text or tweet often during movies. But again, a theatre can't start differentiating between important and unimportant texts.