I was looking around for the Age of Wonders 1 manual today as it's got quite a lot of interesting fluff - stories and drawings and the like - and was a little surprised to see that GOG hasn't got it. I was even more surprised to see that GOG hasn't got the manual for Age of Wonders 2/SM, because IIRC that manual has some information that isn't available anywhere in-game (specifically, what impact reputation has and how it's determined).

Of course, these manuals have been posted as PDFs here and there on the internet, so it's not a big deal, but I'm curious - why don't any of the AoW games have manuals on GOG?

Their absence is listed on http://www.gog.com/forum/general/gog_games_missing_content_broken_games_incomplete_version_variations_etc/page1 but I don't know whether the staff have ever commented on it.

AFAIK, it's a rights issue for AoW 1 at least. Not sure if they went with different publishers for the manuals of the later games.