Bashing around in twin pistons I used to wear ear plugs under my headset. I also know of guys who have flown loud turbo props that wear ear plugs under their headset. The reason for it is that we are exposed to a loud environment on a regular basis
I dont know about wearing ear plugs to a concert though. I wouldn't think that you could go often enough to cause any serious damage.
I think the "Boys harden up" line should stand.