From what has been explained to me, one dimensional is like having a light source and you sit on top of it...meaning there is no direction, there is no shadow or time, you can't go anywhere because you're everywhere at once and you don't have freewill.

Now, some civilizations are fine with this, but you have to understand how photons coagulate in the dimensions "above" and "below" this one and what this means for free will.

Also, there'd dimensions are VERY slow to evolve because there is no "struggle"...meaning you have no wants because you are everywhere at once, with everything at your fingertips...but it's not as nice as you think it is...