If a club allows cell phones, what you'll see is players adapting to it.
Personally, I'd just insert it into my scotch games with a new rule: if you use your cell phone during the play of a hole, it's a one-shot penalty for delay of game and 1 point for the other team. That'll keep it at "emergencies only" faster than anything I can think of...
That's fine, so long I can put something in there about use of a long putter
Seriously, I don't see what the big deal is with using a phone to check/return text messages or check voicemail. Actually making/taking a call should be reserved for rare circumstances, and if the discussion is going to last longer than a minute or two or more than a couple calls during the round, the person really ought to review whether they belong on a golf course. But the things I mentioned can be done quietly during a momentary downtime while waiting on the group ahead or someone in my own group, and can be interrupted immediately and picked up later if the downtime resolves itself. Its incredibly disrespectful to be blabbing away on the phone while others in your group are waiting for you to play, unless it is a true emergency - the type that generally means the callee needs to ditch the rest of the round.
Even though I wouldn't like to be subject to it, I can understand the blanket bans, because despite the possibility of reasonable and respectful use of cell phones, too many people think they are too important to respect the others in their group or on the course, and will delay play or disturb others. I wonder how well these bans are really enforced though - if someone has their phone in hand as the ranger rounds the corner, do they get told only to put it away, just to pull it back out again the minute the ranger is out of sight?
I'll bet the only places where the bans really work are private clubs where the majority of members (who are probably mostly retired) enforce it on the minority themselves via peer pressure.