Why does Adobe Acrobat Reader require a restart when you update it? It's a piece of software that reads PDFs. Just what else is it installing/updating that requires a total OS reboot to "complete" the installation?
A bit of Googling indicates that it's to allow the OS to install the Adobe "Speed Launcher" - is this it or are there other components that are more tightly into the OS that it must absolutely have to have closed so that it can update them?
Edit: Any way to give half points to the two users that gave plausible explanations for this particular issue? I'm under the impression a combination of both of these answers is the reason why the restart is required, unless anyone has additional knowledge of what goes on behind the scenes are an Adobe update.