Had the same "problem" while fighting the (mini-)boss at the lighthouse. I made the oil barrels explode, and a thick black smoke hovered over the burning oil, causing me to lose line-of-sight with the enemies.
I used this to my advance though, by making the enemies come to me instead of charging in blind. By the time they reached me, my ranger and mage would have had plenty of opportunity to whittle down the enemy's health, and my two warriors could easily finish them off.
As soon as the fight was over, the smoke cleared.
I think it forces you to be mindful of your surroundings/enemies, and try to find ways to use these elements to your advantage. I like that the game "punishes" (if you know what I mean) you for rushing into combat. I've had to reload earlier saves on many occasions because I accidentaly blew up something, killing half of my party.
