Not everybody would want to have to make a seperate partition for the pagefile. Sometimes it can be handy to just defrag the existing one. Also, it's not just the pagefile wich cannot be defragged while running Windows. There's more stuff that qualifies for that, including the Windows Registry.
It would be very nice if Defraggler had an offline-defrag option. In that case, ALL files could be defragged, including the pagefile. I know PageDefrag: http://technet.microsoft.com/en-us/sysinte...s/bb897426.aspx , already does that, but it doesn't seem to work (very well) on Windows Vista.