does it function or is it for cosmetics??

This defiantly would function as long as you adjusted it right. If you look at inside rear of the car where you see the mold that connects the two towers thats mated to the floor also. That U shaped piece from the factory serves the same purpose. All the products does is enhances/ adds to that stucture.

My plans are to cut that same structure out completely and brace the two shock towers togehter from the top which will add to my already roll cage I have now. The route I'm going doesn't save weight but will give great structure with possible adding a fuel cell.