As someone who treats patients with RSI injuries the trackpad is what is ergonomically terrible, worsening with how close the laptop is to your body and how much you have to constrain your arm, wrist, hand, and fingers for hours every day. I'm not saying a touchscreen is a panacea, but that mixed use where you give your trackpad hand a break and do *some* things on the touchscreen is EXACTLY what I'm talking about. For me I like to scroll, pinch, and zoom with my touchscreen, but will probably use the trackpad as more of a mouse to select smaller things. This whole vision of your arm hung in the air with the laptop 3 feet in front of you is not how any body uses their laptop. But really the name of the game with RSI is the "repetitive" part, any repetitive action is bad, even touchscreen use, that's why a mixed use model is a lot better than just a single input model. That's why you should also incorporate a mouse (especially ergonomic mice like vertically positioned ones) or possibly even a trackball into that routine just to change around which areas are getting repetitively abused.