To attempt to answer the OP from a current airline pilot's point-of-view:
...the skies are full of landing lights from 10,000 ft down day and night. Often at night these lights can be seen as a glow as the aircraft depart or arrive through cloud. I often wonder how these pilots are not distracted when flying through cloud with landing light reflections in their eyes. Certainly their night vision must be seriously compromised - or is that not a safety factor anymore?
As mentioned by others, it's a common SOP these days. As far as distractions go, on the types I've flown it's not a problem. If you're in an aircraft with manual engine anti-ice, it reminds you to turn it on if you can't see the 'visible moisture' on account of it being dark outside.
As far as night vision goes, I much prefer a brightly lit cockpit where I'm awake and not mistaking one button for another in darkness. An aircraft with lights/strobes on can be seen at a respectable distance, more so if the selection includes landing, wing & logo - so I like to make myself visible to the world in the same fashion, especially when over Africa et al.
We takeoff and land from lit runways so "night vision" wouldn't be of much use. I have a feeling that the intensities of modern approach lighting installations are such that they would probably ruin any adaptation, anyway.
While I understand it is common practice (and even a Regulation perhaps) for aircraft to have landing lights on below 10,000 ft, surely good airmanship would suggest these lights should be switched off while in cloud or poor visibility in order to avoid glare and distraction to the crew caused by the lights reflecting back off clouds?
As mentioned earlier, not many people find this a problem and if it is, the remedy is in front of them in switch form. If operating in
very low vis. for takeoff, I sometimes compare lights off to lights on to see what gives the best results in the conditions, much like trying low/high beam in a car when it's foggy.
From what the engineers tell me, on modern aircraft the landing lights are powered up at a reduced level all the time to keep the filaments and bulbs hot, so when brought to full output there isn't much thermal shock.
Or is it a legal minefield because there is a rule that says landing lights must be switched on below 10.000 ft in climb and descent? Are SOP's that pedantic that good airmanship is no longer a desired factor in flying airliners - but strict adherence to the book is?
I think current wisdom is that it is better airmanship to make yourself as visible to others as you can in a congested environment and hope that they do the same for you. I, for one, have no argument against this particular SOP. If I did, my employer empowers me to use my discretion to vary any SOP I wish to in the interests of flight safety, if I can justify it...