Game pads that use keyboard keys with custom switches and unique form factors are where I think we're heading. Like the razer tartarus v2, which I have. It is great for gaming, better than a standard keyboard that uses identical switches, but still not ideal. It is similar enough to the layout of a keyboard that finger positioning can be the same and the learning curve is smooth.

It's closer to your "ideal" but not there yet. And I completely agree that we need to go in that direction.