I recently used this https://makerworld.com/de/models/1765102-10-inch-mini-rack-g... to generate various mounts for my home lab mini rack. The idea is that everything needs to fit into the same width of rack, but every device is slightly different so custom creating these becomes annoying quickly. This generator was a godsend
So the appeal for you, as the "user", is that you can easily customize the parameters which are made customizable by the designer and get a suitable model without requiring proprietary software (or any software at all). I can see the appeal of that.
But I assume the designer spent quite a lot of time, creating this in OpenSCAD and make it customizable. He was also restricted to making shapes which are easily described in OpenSCAD, where he might have gone for a more elaborate design if it was easy to do.