As someone who is constantly on the road, having a built in sim card for connectivity is something I'm super excited about. This could be the 2016 MBP we wanted, but switching to windows still sounds difficult.
Why do you find that better than tethering to a phone? The last thing I want is a separate mobile account for my laptop.
On the one hand you've got a laptop that is online the whole time, on the other hand you've got a situation where you have to have to fiddle with two devices to get online.
Moving onlineness from a deliberate, modal thing to a continuous thing changes the way you interact with the network.