Chill out, Dude.
I often wonder how these pilots are not distracted when flying through cloud with landing light reflections in their eyes
Well, while flying through cloud I usually don't look out the window as all clouds look similar inside - I've seen it before. What I can see on instrument panel is what I'm interested in. No glare from landing lights there.
Certainly their night vision must be seriously compromised
Dude, I'm IFR flyer, usually operating in at least class D aerospace. I definitively don't expect night VFRers to buzz around in clouds or that I can see them at night, in clouds - blinded by landing lights or not.
I don't use approach/flare lights on CAT 2/3 night approaches and if I estimate they'll impair my landing (eg. in blowing snow) For everything else they're on from runway to FL100.