I myself work in IT and am call 24/7. My users often need help and I can usually fix their problem quickly. If I had to go cell phoneless, then I would just have to stay home.
Cell phones have opened up the world to those of us who are on call. I think that one person is not more important than anyone else. If a friend I took to lunch walked out on me because I took a call, well then that would be my last lunch with that friend.
The problem is not primarily with the technology, but rather the fact that some people refuse to be discrete in their use of it (though there are a few technological tweaks that could be helpful). Actually, I would think that with some technological tweaks one could construct/program a cell phone such that a theater patron could communicate during a show without anyone being the wiser. Combine a headphone with a means of silently responding by touch only. No light to disturb other patrons, and no noise except the sound in the earpiece (which, being inside the earpiece, could be essentially inaudible to everyone else).
Then how do you expalin the Secret Service?