Well I didn't disable it and I'm the one who did Windows installation and the only person using this PC.
I do remember running a Command Prompt command to enable display of "non present devices" in Device Manager, to be able to delete drivers & devices after I've changed motherboard and CPU. So as to not have to reinstall Windows.
I do have UAC turned off... no idea if that has something to do with this driver(s) thing. I wouldn't expect turning UAC off to "disable" all metro/modern app but it did it, so... who knows with Microsoft
I already have another Windows 8.1 x64 copy running inside VMware so maybe I will try installing RNDIS driver on it to refresh my memory.
edit: I do get that error windows if I just try "right click>install":
On my PC that already has working USBNetwork setup.