NavList:

This is something that is a bit of a pet peeve of mine. Some people seem to like to have every flood light on all the time. In addition to the astronomical degradation, light pollution has detrimental environmental effects, and causes difficulty in visibility as you mention. So many vessels are going around with lighting that seriously disables their ability to see anything at night. There is a tour boat here (Kingston, Canada) that has the passenger area in a dome forward of the wheelhouse (see photo). At night you will see it going by with flashing coloured lights, and I cannot imagine seeing much with that party right in front of you. Not to mention when you see another vessel the excessive lighting often makes it difficult to identify what it is doing, not to mention impairing your own night vision.
On the ship I operate and am very rigorous about no lights on deck when underway, and flood lights are only used when needed, not left on all the time. Other captains have different philosophies.
In port I think some may have procedures requiring lighting for security reasons. I do not think it is explicitly required, but vessels have been required to create security plans (the security course I took was officially the most useless course I have needed to take, but that is a different rant). Deck lighting is an easy thing to put in to create some content for the procedure, regardless of how effective it is or whether there is much risk that actually needs mitigating.

File: