Xeno, "We have enough fantasies in life when we are awake, so why add fuel to the fire by claiming significance for a state of experience that is far more disjointed, wandering, and uncoordinated?"
We really don't have a choice in the matter. It's a fact that people dream and it is a separate state of consciousness. From my observation, animals and insects rest at night. So, I would guess they too might experience animal or insect dreams. IMO, dreaming is part of Nature. As such, I've proposed here in this forum that dreaming is really another dimension above the space-time continuum. IMO, at the level of the human dream state, we can see things or events that are above the space-time horizon. This is the reason why some people can see in the distant future and in the distant past, even extending to past lives. Further, IMO the planets, particularly the Moon, affects the nature of our dreams. IOW, our mind is connected with the cosmos on a daily basis. Personally, I found that my dreams are pleasant when the Moon is in the nakshatra of Krittika. This is the area of the sky where the Pleiades is located in the sign of Taurus.
