Another argument for the horizontal orientation is strength. Since this connector will be subjected to push/pull cable forces, distributing those forces over a larger PCB footprint would be advantageous. I suppose they could strain relief the connector to a panel, but the photos I saw don't seem to incorporate that option.
I'm not dissing the vertical orientation, just saying it's often suboptimal for multiple reasons. I use vertical connectors only when demanded by some outside requirement, otherwise horizontal are generally better.