There really is no question that if there was an editor released along with the game, it would help the game a great deal.
However, that does not mean that it is cost-effective or even feasible. The starcraft maps, for example, were built by Blizzard using the very same editor that came with the game. The single player maps could be opened, with a bit of work, from the game files and edited (putting them back in was a different story). If Demigod wasn't built from the ground up with these editors in mind, then we have to ask ourselves how much it would cost today, in terms of both money and time, to release a working editor.
Obviously demigod maps were built using some kind of tools, they didn't hack em togheter in winhex. Hopefully they can be released, in time. But I doubt we will see any kind of editors with triggers.