It's not really that much data
It seems like a lot, but they are covering a lot of bases. Since XP Windows, Windows Update has not only updated the Microsoft Windows packages, it also updates all the Microsoft software found on the machine - it has to check for every conceivable Microsoft software that may be on the machine.
THEN it has to go over every conceivable piece of hardware to check if the hardware's manufacturer has registered a new driver update for said hardware. That is a lot of checking, but in most cases "the sheer amount of data" is a lot of BLANKS. So the list is long .. but I would venture much of it is left BLANK most of the time. And now some people have signed up to "Insiders" so that has its own list of stuff there if the person signed up for that, but nothing much would be sent if you didn't turn that on.
They also have to check for every conceivable language pack that might be installed to make sure any package installed is in the language. Windows supports a lot of languages. But again most people have only one or two languages installed.
And they have to check if there's been any crashes or other events so that they can fix bugs.
It seems like a lot, but yeah, it's just basic stuff, techno-gobble-dee-gook, I would venture much of it sending nulls on most machines.
For comparison's sake, you should see what a simple webpage visit involves! Handshakes, protocols, packets, transfers, acknowledgements, blah blah blah ..
I personally do not use Windows 10, but 'the sheer amount of data' aspect of Windows Update doesn't bother me in the least.