It can be. Concrete isn't a great insulator, but it can moderate temperature changes, so if you have big swings between the day and night, it will keep things cooler in the day and warmer at night, which can be helpful. But if you get a heat wave where it stays hot at night, you're going to be real warm inside the next day too.

This article mentions 100 and 200 square feet buildings, so I don't think there's gonna be much in the way of internal structure. I could see an inflatable structure with 'tubes' at certain places for wiring and plumbing to pass through, which would save cutting holes later.

But like everyone else says, there's easier ways to get the frame up faster. What makes construction slow is coordination between the many different trades that need to work in the same area. With many parts in sequence, and each trade having high utilization, scheduling is difficult --- either you plan with large gaps between trades, or you blow up everyone's schedule when one trade falls behind for whatever reason.