Because it's really not that important, you're giving it too much weight.
For me it is very important.
Would you not find it more immersive and dramatic, when e.g. you attack a bands of goblins, and it starts to rain and a thunderstorm roars over you, while swords clash and spells are cast? It can be pretty cool. Always sunny gets borring fast.
As for Astarion:
Obviously you like that character, and he is (somehow) important to you. Not for me, I don't care about that companion. But you will not hear me saying, that it's not important, you are giving this character too much weight