I couldn't agree more with your review's conclusion. The cable management issues just ruin what might be a work of art.
I can imagine several long U shaped pieces of aluminum that could act as channels or gutters for cables, and would hide the cables in your build on the back side of the case. Or just have a large removable flat piece of aluminum and several one inch spacers to cover the cables and provide a one inch wide cable area behind the mobo tray. The spacers used for the glass side panels are what I have in mind.
Does IN WIN have an example build of how they see a build being done in this case?
I've considered an IN WIN 904 for a glitz build, this review helped.