I wonder how far it goes before the first trail stone that winds up in the belt puts an end to the trip?
You gotta be kidding. Belt drive? 
"Burly but nimble"..... I had to laugh at that. Few people can manage a bike of that heft offroad.
If people are buying it for style, to park at starbucks or whatever, have fun.
But to seriously go offroad? I'd prefer a Himalayan, frankly. Give me low ( field fixable ) tech, and light weight.
They are offering a chain drive option.
Let's be honest, the majority of big 'ADV' bike buyers are not purchasing them because they are doing a 'Long Way Roung' trip. They are purchasing them because they want to look like they are doing a 'Long Way Round' trip.
As you mentioned, the best motorcycles for true long off grid trips are often the most simple and easily fixed in the field. KLR is one example. The bikes have been around forever, barely changed, and parts/mechanics can be found in basically every country.
Finding modern BMW parts in the middle of Africa is probably a lot harder then KLR parts. While I'm sure it can be pulled off with enough planning, I highly doubt anyone is buying this Zero with some idea they are going to circumnavigate the globe on it.