At E3 2012 they showed off some of Arma 3s lighting which looked amazing. It also appeared in the Arma 3 Alpha but was removed for some reason. Here is the Arma 3 Alpha change log where they removed it from the game: http://store.steampowered.com/news/10701/
As you can see from the link above there were lots of lighting/environmental 'tweaks' that removed them completely.
Please add them back to the game as it would be much appreciated (Or as TOMMEH discussed in his ticket to just simply add it as a graphics option.)
Some links to some early Arma 3 videos:
https://www.youtube.com/watch?v=mIwfS8uJJIk
https://www.youtube.com/watch?v=I0untAgEncI&list=UU9ZQYIa5fX_Pf75508JtPBg
Here you can also see the flash light lens flare was removed:
https://www.youtube.com/watch?v=lwXw0g2fweA&list=UU9ZQYIa5fX_Pf75508JtPBg
The Arma 3 2013 sneak preview trailer:
https://www.youtube.com/watch?v=83NkPguw9Jg&list=UU9ZQYIa5fX_Pf75508JtPBg {F23965} {F23966} {F23967}