I think you've just made a very valid point. I find cockpit(jet) noise tiring and a good anr set with intercom is bliss, especially across africa for 7 hours listening to hf and vhf repeaters that sound like the microphone is inside a metal bucket. Anr sets allow half the volume and twice the discrimination on the radio. I can see an argument for leaving one ear off on the take off roll just in case some engine abnormality manifests itself audibly before anything else, but in the cruise...why go deaf if you dont have to?