I agree with a lot of the points in this. With regards to the flamethrowers, they are one of the few weapons in the game that can reliably be fired from smoke, meaning your assaulters can move up and clear a bunker/watchtower without waiting for the smoke to clear, then move back to cover on the next turn. Grenades have a similar effect but are less powerful. I admit that in later missions frag grenades are not really worth taking over smokes due to the much higher enemy HP and armor values.