As a business traveler, I look forward to those precious few hours where I can be "off the grid." It is such a relief to be disconnected from my cell phone for a few hours. Also, importantly, no one wants to be forced to sit next to someone incessantly jabbering on their cell phone during a flight.
I don't think that in-flight phone calls should be banned because there can always be some sort of emergency between any one passenger and access to a helpful source is crucial. If you know or are expecting a critical medication while you are on the plane and have forgotten to bring with you, a call from a cell phone, a text or an email can help save your life to transfer important information to a source that can readily provide it for you.