[Goronmon]

I'm sorry but your first sentence is just bad logic.

I don't see a problem with the logic. If personal electronic devices could truly cause interference, then just reminding people to turn off devices seems like pretty weak protection.

How many people intentionally or unintentionally leave an electronic device powered on during any given flight? I know I've forgotten to turn off my phone a couple of times in the past.

Only going as far as reminding people to turn off devices is the equivalent of airport security checkpoints that just have a person standing there reminding people to remove dangerous items from their bags before boarding.