It's mimicking the g-forces you'd feel as you accelerate / corner, which it looks to do very well.
Yep, at first I too thought "wtf that's extremely exaggerated!"
Then the one comment on that page made perfect sense.
You don't get the benefit of actually feeling true G-forces, so that platform exaggerates movement to help mimic the weight shifting one would feel at every moment, where your weight would feel concentrated.
If it was surrounded by solid black, I'd imagine that'd be awesome to play.
But when your constantly looking at the screen, the immersion of weight-shifting plus the screen always being front and center would probably help eliminate the problem of your eyesight correctly gauging orientation and thus breaking the simulation.
I wonder how much that cost!! Do want!