In wartime pilots would sometimes be forced to fly very low and the barrel roll does have some use in combat. But dangerous maneuvers are only supposed to be tested in a flight simulator, not in actual flight. This attitude had greatly reduced the accident rate for jet aircraft. Seventy years ago it was 200 or more accidents per 100,000 flying hours. A half century ago it was closer to 30. A decade ago the rate was under ten and now it’s under five. Flying combat aircraft has never been safer or more boring.
While fighter pilots might engage in dangerous activities off duty (snow boarding, cross country biking, hang gliding, and other “extreme sports”) while on duty safety has become increasingly, year after year, a major consideration. Often, it is the only consideration. Getting useful training done is a distant second. This could be seen in Afghanistan, where helicopters had to learn some dangerous flying maneuvers on the job because they were "too dangerous" to do in training.
Pilots have long fought with the safety crowd and civilians annoyed at low flying aircraft. The pilots have been losing, leaving them to fly low, fast, and in the dark during wartime but without much peacetime practice. This is particularly dangerous for helicopter pilots, as the jet crowd has been able to keep their warplanes way up high (because we have destroyed the enemy air force and anti-aircraft missile). The choppers still have to get down low, and in Afghanistan this has been particularly dangerous because of the weather (hot and stormy or cold and icy) and altitude (3,000 meters or more up in mountains, where the thinner air reduces a helicopter’s effectiveness). Active duty pilots rarely complain publicly, as that would be a career threatening move. But many ex-military pilots periodically remind everyone that the problem has not gone away. And sometimes lawsuits, by civilians trying to ground the low flying aircraft and helicopters, brings out the need for dangerous peacetime training.