eww, 2 in 1's are immediate tech-turn-offs. Essentially forcing people to pay for a feature that is unneeded for many people and unwanted. It would be like if you had to pay for a mouse with your laptop, even if you never intended to use it over the trackpad.
PS. 600 nits, 4k etc.. does not make the display look good. I just told you that I was looking at high end laptops with 4k screen xps, and the microsoft surface book (new ones), and they have weird "spaces" in between the panel and the display, the glass and the pixels. It makes even the $3500 surface book laptops look like they're from 5-10 years ago.
Also, why would you need a 4K display on a laptop screen that's only 13-15 inches. It doesn't really make much sense, just a drain on the battery for something you can't even notice. I have to be supremely close to the screen to see the pixels already, if it were 4K (Retina Macbooks are 3K) it would certainly be a bit nicer but is it worth it for the battery power hit I'm going to take. If the screens were a bit larger then yes 4K all the way. Like around 19-21 inches. I would rather buy a separate display to plug into for 4K/5K/8K/15K etc. like the 27 inch 5K displays. That makes sense because it's so large that if it were only 2880x1800 like the retina macbooks then it wouldn't look as crisp as your laptop screen which would be a bit of a bummer (if you're like me). If we were talking about monitors only, then yes, again, get a 21.5inch or larger and make sure it's at least 4K! But for laptops, part of the greatness is the portability/battery life balance.