White noise for an extended time damages your hearing.

If you want isolation from other passengers, wear some headphones. But noisy engines are not good for your health.

Maybe that is a legitimate concern for flight attendants, but I totally reject there being any measurable impact on my hearing from riding in a 737 a few times a year. Particularly when I also do other activities like walking down sidewalks next to traffic, which is typically louder and very often MUCH louder (every time an emergency response vehicle drives by blaring a siren which incidentally incorporates white noise.)

Headphones and earplugs are uncomfortable when worn for several hours in a row, either because they are inside my ears, or because they are bulky. This is a matter of comfort, particularly since I try to pass time on planes by sleeping. A noisier commercial airliner, all else being equal, simply is more comfortable than a quiet one.

(I dare say sleep loss and jet lag have a more measurable impact on my health than whatever hearing loss is induced by a typical commercial airliner.)

>like walking down sidewalks next to traffic

Traffic noise is usually much more intermittent, unless you're walking next to a busy freeway. You just hear cars as they go by, but it's not usually a constant. Ears handle intermittent sounds much better than constant noise, even when the intermittent sounds are much louder. It's a lot like radiation exposure: it's cumulative.

>A noisier commercial airliner, all else being equal, simply is more comfortable than a quiet one.

Honestly, you sound like someone who already has a lot of hearing damage.