Two Issues:
As a professional County Veterans Service Officer, I have not heard anything about not giving service connected disability for hearing and tinnitus to vets. AND, the individual Services have NOTHING to do with whether or not the vet gets SC Comp for any condition, that's a VA thing. My guess on that is that he services, or concerned commands, are trying to get the kids to protect thier hearing more. SGLI for willful and self destructive behavior is a different conversation, and is rightfully denied in proper circumstances.
As a Spec Ops kind of guy in the AF, YES, we wore hearing protection under ALL live mission conditions as early as the early 80's. They were fitted hearing aid type deals that fit in the ear and allowed us to hear low volume sounds at amplified levels and completely blocked out high-intensity noises like ordinance and gun fire. (Kind of like the electronic ear muffs that i use on the range now. If the unit wouldn't pony up for the gear, then we bought it ourselves. We discovered early on that once you engaged, if you don't have the protection you become deaf for the remainder of the engagement, which is a problem in itself, and if you just wear muffs or plugs, you're deaf from the insertion on, which is just as bad... I did not regularly see similar equipment on other service teams that we operated on. (Just one more reason I'm glad I was an airdale...)