There are two real possibilities:
1) Interference is not a real danger and not the cause of the issues you have on occasions experienced.
2) Interference from mobile phones is a genuine danger to aircraft systems.
If (1) is true interference is not a valid reason to ban electronic devices.
If (2) is true the current safeguards aren't high enough and the protection should be greater. If passenger jets are vulnerable to interference from normal 3G phones then it is a potential form of terrorist attack to create massive amounts of interference at a critical point in the flight deliberately. Probably much easier than messing about with binary liquid bombs.
Edit: Note that I believe that case (1) is by far the most likely and that I think that 10-100 times normal power device would probably be feasible if you didn't care about battery life although it might make sense to hide it in a laptop and use a bigger antenna than keep it in a phone package.
All of these signals are flying around the atmosphere all the time. Distance certainly plays a role in effective power at the point of reception, but a tiny 0.3 watt cell phone transmitter isn't bombarding the aircraft with any more RF than an FM transmitter that is miles away from the airport.
The reasoning just doesn't stand up.
In the real world, regulations are the result of trade-offs and not absolutes. It's just that the current trade-offs seem to err on the side of safety.