It is a safety issue, not a cosmetic one
Oxidized lenses scatter light instead of projecting it. Measured output through a badly yellowed housing can drop by more than half, and the beam pattern spreads โ which means less light down the road for you and more glare for oncoming drivers.
That matters on unlit stretches like the causeway, FM 646, and the rural roads around Santa Fe and Hitchcock, where the difference between a clean and an oxidized lens is real stopping distance at night.