The entire purpose of the PC bottom is to address the issue of having an unsightly acrylic strip in the middle of the keyboard. It's ugly, and it's not aesthetically pleasing especially when the RGB is off.
The reason for the PC bottom, as stated in the original post - is to address an issue for two types of people. Those who love rgb and those who don't. If you want rgb, it's going to glow very very nicely. If you don't want RGB, turn it off...once you turn it off you don't have any dead plastic detracting from the rest of the aesthetic of the board. With rgb off, you won't even know it has it.
I am not making an acrylic layer to sandwich between two pieces of aluminum on this, and nor will I ever design any future boards to have it either.