As you say, there's a class of apps that works best on a phone and another that works best on a laptop. But there's also a class of apps that you'd want to run everywhere, for example all the addictive social media apps. For these it becomes more of your preference between touch vs point and click interfaces. This is what Windows has been trying to do, offering both paradigms in one device. I've talked to people with these Window devices who will switch between using the full-screen/touch and the windowed/mouse version of the same app based on their context. It's nice to have the options.