I think this battle is long over and done with, but the Ethernet jack is not that big. A Thinkpad T470s/T480s has it and it is plenty thin. There are even some laptops with a collapsible RJ-45 port which allows it to be even thinner.
A USB port is also not that thick yet it has been dropped on many recent laptops, although a Thinkpad X1 Carbon shows it is possible to have USB, HDMI etc on a 2lb / 1kg machine.
A serious question: what is the advantage of thinness for you, personally? I have several laptops and I'm on the move all the time. The only disadvantage of thicker ones for me is weight - but it's negligible, even when I'm cycling and my laptop is in my backpack (or, sometimes, laptop bag). Weight aside, the thinness itself has zero advantage for me. I'd much rather have all the functionality removed at the cost of it (not just Ethernet - I care much more about user-replaceable SSDs and RAM).
It's aesthetics/psychological. Weight is also important to me because I travel and the thinness affects my perception of the weight. It's a bit strange that the new Pro feels thicker than my old laptop, the 2015 Macbook Pro, despite actually being thinner. It's because it doesn't have the taper that the old laptop has. Take a look:
The parent doesn't mention the T480, but the X1 Carbon which comes with a full range of USB and HDMI ports. The Macbook Pro is 1.55cm thick, the X1 Carbon is 1.49 cm thick.
Lenovo also sells the T480s, those are not substantially thicker (1.6 cm high) and beefier and come with a built-in ethernet (!) port.
I mentioned the T480s. The T480 is much more user-serviceable than a Macbook Pro, with upgradeable RAM, SSD, Battery etc, and much cheaper, so not a valid comparison.
