I streamed the pilot yesterday from their webpage. I liked it.
The "if the aliens have 6 legs why do their robots have only two?" question irritated me a little. We have 2 legs and our robots on Mars have 6 wheels, so it should have been a non issue. Since the show brought it up in an obvious, trying to be subtle, manner there is going to be some deep (and stupid) social commentary behind it. I have a feeling the reason for the two legged robots will disgust me enough to stop me from watching it, but for now I'll enjoy the show.
I think you are a little confused, or you missed a bit of the plot. Those aren't robots, they are exo-suits. You can tell they are exo-suits not only from the plot explaination, but because they have legs. Wheels/jets/whatever are infinately more cost-effective, energy-effective and easier to engineer than robot legs. The only reason you would make a robot with legs, aside from asthetics, would be because it's a suit and there are real legs to contend with inside.
A robot, a car (lunar lander) and a exo suit are totally different things.
It seems to me that the dialog in that scene was poorly written though. You look at the crab aliens and it's obvious that they are too big to fit inside those walker shells.
And yes what you are thinking is probably the case. Either that or it's a master/slave class of two seperate aliens.
I've got to say, the show is getting more interesting as it goes on. Still not great, but at least it's original.