Does a hybrid laptop make sense?

Recently I've been thinking a lot about hybrids. Here are my thoughts, please let me know what you guys think or have experienced. For me a tablet is a device best used for under 2 hours/day and only in the absence of a laptop (both because of performance and inferior ergonomics compared to a laptop). There are a lot of products (such as the surface pro) that try to combine these two into one. I think it does not work. Here is my reasoning: One of the major differences between a laptop and a tablet is the screen size. A tablet is usually smaller. So what is the appropriate size for a tablet and laptop? According to THQ: (diagonal size of screen * 1.2) = distance from screen This would mean that if you sit behind a laptop on a desk, the laptop should be around 15-17 inches. If you hold a tablet in your hands the screen should be around 8-10 inches. From my own experience, I absolutely approve these sizes. To make an example, the surface pro has a 10,6 inch screen. That's netbook size. If you've used a netbook, I think you agree that there not comfortable to use 4 hours/day behind a desk. You could use an external monitor, but monitors are normally at least 20 inches, they take space, and apart from a few productivity cases (such as programming, photo editing) the average user is too close to a 20+ inch monitor. What do you guys think?