Since the story came out people fixated on "lol he used a shitty gaming controller" but really that is one of the least sketchy design choices in the entire rig. Why reinvent the wheel and make a custom set of controls that are realistically another huge expense and potential failure point, when off the shelf solutions exist for that component?

The corners that were cut are the ones involving the viewport/nose adhesion to the ships frame, and the structural integrity of the carbon fiber hull itself. They had test data suggesting it was a bad idea to engage in repeated dives with their design, and an even worse idea to operate at the depths they chose. They decided to ignore that.