we occasionally must remember that this game is old. it was built for what... 2003 spec computers, where multithreading was non-existant, and computers were quite simply not as powerful. (and hell, the game still gets laggy when you got 10 players with maxxed fleets)
While I am sure rotating turrents will be in sins 2. (I will be rather unhappy if they are not)... the game engine does not support anything besides stationary meshes.
And, on rotating planets... at one point in the beta(alpha?)... the planets DID rotate... but... it was removed for the rediculous ammounts of chaos it played on the phase lanes, and the players minds...
there are lens flares in game. they are just not rediculously noticeable.
shadows would be a bad idea... you see... space is really really dark... and if it wasnt for the ambiant light in sins... you could see preety much nothing depending on your point of view... (me, personally, always start the game by rotating the map so that the star is at the top of the screen... aka... I am looking at the dark side of everything constantly)