I am one of those pilots. I've been an airline pilot for more than 20 years.

Cell phones can interfere with aircraft systems. I have seen such interference first hand. When everything is working properly, a single cell phone shouldn't interfere but things don't always work properly and we aren't talking about a single cell phone. The risk of having some phones on, but not on an active call, is relatively low but low doesn't mean non-existent. When interference occurs, it will not normally cause an accident, but it could. Things as simple as a burnt out light bulb have started a chain of events which led to airline crashes in the past. Reports of interference from passenger electronic devices are submitted regularly to the aviation safety reporting system (ASRS).

Aviation safety is about identifying and managing risks. There is a risk associated with the passenger's electronic devices, including phones. Measures are taken to minimize these risks in ways which are practical for the passengers. Confiscating all cell phones, computers, DVD players, etc. prior to flight is not practical and is not necessary. The risks can be managed in other, less onerous ways. The current policy doesn't result in 100% compliance but without it there would be a hundred, or more, active cell phones on many flights and nobody can predict what that much RF in the cabin might do. It would certainly result in a significantly higher risk of interference than what we have now and there's no reason to take the additional risk.

This idea that if there was any risk at all the activity would be banned demonstrates a naive view of risk-management philosophy. If such a strict risk-avoidance policy was used we wouldn't fly as there are always risks.