In the past, I've encountered Windows not letting me shut down a machine when "critical" updates were downloaded but not installed. I've seen Windows allow me to defer an installation for one or two or three shutdowns, but at some point not let me turn off or restart my machine until I actually installed the updates.
That was a potential problem here, I felt, and why I didn't think I could just ignore it. Parts of the "system" in the local machine didn't seem to be understanding what was happening... and in fact I was prompted to install at shutdown after I thought I'd installed this particular set.
A big concern was that if the machine wasn't recognizing the installation, I might not be able to do a reboot when I wanted to.