Goodness me this is all getting a bit precious isn't it?
You can't really equate office environments to aircraft cabins in my (ahem) view. If someone's watching a screen (either provided IFE or a personal device eg tablet) they're doing it for entertainment's sake. Office monitors tend to have some form of anti-glare function, and yes, the environment can be modified somewhat to suit (plus if someone's trying to rest/sleep in the office, well that's a whole other situation
). I would suggest if folks are in the office environment watching video entertainment, movies etc (for their job) they probably have a more dedicated environment/area for that. Although I may have had cricket games streaming while I did other work, but that wasn't being watched all the time either.
Yes, a lot of people also work on aircraft on their laptops/devices too, and probably prefer less glare if posible (again, why if I notice someone using a screen next to me and I'm in the window I will put the blind down out of courtesy. I normally listen to audio in flight myself).
As pointed out above, people often are on flights in all kinds of different circumstances. You can't assume that everyone getting on that daytime MEL-SIN has started in the right place or even have the same needs for rest either.
I fully get the argument about >12 hour flights being kept in darkness when at least some portions should be in daylight (but then there are other times where you can fly 17 hours through a very long night eg DFW-SYD/MEL).
I see a cabin environment as a shared space with other people. I am a window seat guy, but I try to be reasonable about it and aware of the entire cabin. Yeah, that one person letting dawn sun stream into a cabin can really be annoying for other pax so I wouldn't do it. Others feel otherwise and that's their right. However, I've also been that guy in the US who does open the shadw during taxi/takeoff/landing because I want to, and I also think it's a safety thing, but generally if the rest of the cabin is dark, I'll shut it otherwise out of respect. If a few others have their windows open then I might go half/half and again be aware of who is around me.
It's a bit like flying to LAX arriving early morning then taking a transcon - a daytime flight. If the transpacific flight was not good, then yeah I am someone who wants to nap. Yes, sure, eye mask etc (unless I didn't bring one with me) or I just suck it up. That's on me and I wouldn't complain, but I could also definitely understand if people were unhappy if I wanted to keep the window shade open for hours while others are resting, working or watching a device.