Computer players aren't particularly smart, but I think it would be nice to be able to start an all-CPU match in which the player can spectate. I know you can do this in World Party, so why not Armageddon?

There's a W:A screensaver that does this. I don't think there's any particular reason why you can't apart from that it seems a bit pointless. I think it's planned for a future update, though I don't imagine it's anywhere at all on the priority list.

Get the original Worms Armageddon Screensaver (http://www.dream17.co.uk/softography.php?id=40&s=downloads#id89) that was included with the Armageddon Collection or get Bloopy's Worms Autogaming (http://www.bloopy.org/files/Worms_Autogaming.zip) screensaver, which reads WA replays.

Here's the thread about my one. (http://forum.team17.co.uk/showthread.php?t=30525) :)