You bring up an interesting point, but one which could well be playing intentionally into the design of the show. The action scenes we've seen in the trailers so far are from the opening moments of the show I believe, where humanity is at war with a mysterious alien race. It looks garish and monotonous because it is a wide space of emptiness filled with nothing but soldiers and explosion.
In direct contrast, after Red is thrown into the wormhole, he finds himself on a planet filled with endless ocean, a blue sky, and a civilization built around peace and exploration. A world where children aren't made into soldiers, and the day to day life revolves around things other than life-or-death situations.
I'm fairly sure the art direction is deliberate in this case. Which is why it's also likely to be the least "mecha" of the three shows. Since the mech is only there as a means to an end - to show the difference between the main character and this new world he finds himself in.