My only 787 night flights were with Qatar. They automatically dimmed the windows but I was able to override it if I wanted to. I don't know if it made any difference but it was in Business Class.
I do not like window blinds down during daytime flights with the exception of those facing the sun.
I know a friend who is claustrophobic. She likes to sit by a window and be free to look out when she feels the need to. She won't keep it wide open but she needs control of the blind to peak out now and again. The Virgin Atlantic policy on the B787 would freak her out.
People who prefer darkness should simply wear sleep masks and not expect all fellow passengers to have to conform with their wish to travel in the dark in the middle of the day.
It should be made unlawful for airlines to control window blinds with the exception of take-off and landing.