I'm not sure if the glass thickness has much to do with it -- glass tanks aren't made with cemented butt joints like acrylic tanks, rather are held together by the silicon sealant and associated plastic bits.
Look at it this way: You own Oceanic. You are making this cool high-end aquarium. If you *could* remove some plastic bracing and a) cut costs, thus increasing profit and b) make the tank look even cooler, why wouldn't you? Because your manufacturing engineer assures you that the bracing is there for structural reasons, and that your warranty claims will go through the roof if you remove it.
At least, that's how I'd look at it...