Yeah - those braces were likely put there to compensate for the lack of the support and impact-absorbtion of the seats. The seats might even be better at that job than the braces at least, more thoroughly tested in crashes.
In order to be effective, they need to crush and collapse to absorb the impact, as opposed to being rigid and solid, which would transfer more of the impact energy into the vehicle.
Having said that, the braces might also make the structure more rigid and therefore improve handling.