> LG for instance, that make 2 lbs 13.3 inch notebooks and 3 lbs 16 inch notebooks

Those are the Gram series, right? They use a magnesium alloy chassis that feels like flimsy plastic. They are light, but they feel like a something that's going to imminently break compared to Apple's aluminum unibody.

In my view, the Gram trades off too much stiffness and chassis robustness for weight to be palatable to a non-niche audience.

I thought I was in the niche of users that prized weight over all else but I had concerns that a light on-the-go laptop that was so flimsy would last. I returned my Gram due to the fact that I just couldn't get used to Windows (after using Linux and Mac for >10 years) so the build robustness and weight ended up being a moot point