I see your point.
I seem to recall that 90db is an acceptable level of noise to be regularly exposed to as Pilots (although I stand to be corrected).
If you are exposed to noise greater than this, you should wear noise attenuatin headsets, or ear defenders if outside.
As for earplugs on the flightdeck, I think therre would be too much concern over missing r/t calls. Why not just wear a noice attenuating headset?