Increased turbulence could inflict additional stress on engines and airframe, resulting in higher maintenance costs which may offset any potential gains made by reduced fuel consumption.
I always wished they would add more radiation shielding in aircraft. Given the high number of pilots and flight attendants diagnosed with cancer, possibly from greater radiation exposure.
Funny you mention this because many pilots do not reach 70 years of age. I had a discussion with a pilot years ago and he mentioned he was coming up for retirement and did not expect a long retirement due to so many of his colleagues having not lasted long.