For a built-in stereo and AV equipment cabinet I built. I used moveable shelves (on pins), but left the cable slots on the sides (cut away about 4" x 1" section biased toward the back).
The idea was I could rout the cables to the side and then have them drop down to avoid seeing them when the cabinet is opened.
The back side of this cabinet is opened to a closet on the opposite side of the wall so access to the cables is easy.
I like the hatch you show that exits through the stretcher. You certainly are limited in options with a free standing unit but if you can find a way to stash a power strip inside, it'd reduce the power cord count to just the one exiting the base.