It’s funny that you mention mobility. I usually see people stuck an extra slab of USB C to HDMI/USB hub beside their thinnest and lightest Apple laptops so that they can use peripherals.

Usually, except for the overwhelming majority of people who don't use a hub.

(e.g. my Air has two cables running into it, power and display)

Not sure I understand what point you're trying to make, but when I "go mobile" I am typically leaving behind my monitor, my wired keyboard and mouse/trackpad, my backup drive, and most of the other shit I might have daisychained off a USB hub. So I actually see it as an incredible convenience that I can run all of that, plus charging, plus wired networking, off a single USB-C port.

It feels far more "mobile" than a setup where I need to plug/unplug all that stuff into the body of the laptop whenever I want to use my laptop away from my desk.

And those USB-C hubs are like $20, so I can just get one for each spot I move between. Remember the old days of $200 hubs?