I have never seen anyone wear such a headset in a jet
Sooo...YOU haven't seen anyone. So what?
Plenty of people in my company wear them, and I know SAS were supposed to install them in all their 737s (voted best headset after a trial period). Dunno if the economic downturn cancelled those plans? It is THE best headset. By far. Hence the most expensive one, sadly. If you're gonna buy an on-ear headset - then what would be the difference between that one and the !!!!ty ones delivered by Boeing?
Around-ear headsets are much better at reducing noise than are on-ear headsets. This means better communication pilot-pilot and pilot-ATC because you can actualy hear what is being said without having to turn the volume up to Spinal Tap-strength (11). You don't have to shout at each other. Daft? Nope - smart...
You can always buy the FO-version (cheaper
): Bose QuietComfort2 with UFlyMike adaptor.
Your genes (or alleles) will decide how much noise you can take before a hearing loss, and possibly tinnitus sets in. Just as you will not necessarily die from smoking - plenty of people have smoked and lived past 80-90 years. Still, that is not a good argument for you not to give up smoking...
Protect your hearing, wear around-ear quality ANR headsets!