The APIs are mostly cross-platform now, and the SoCs are the same, so the main reason you wouldn't want to just copy a Mac app to the iPad is the touch input. I

The APIs are mostly cross-platform now, and the SoCs are the same, so the main reason you wouldn't want to just copy a Mac app to the iPad is the touch input. If eye tracking is as good as they say, that's a lot closer to a mouse than touch controls.