Interesting theory, Alrik, but I don't think it's entirely the case.
It's certainly true that the storytelling side and the technical side are very different skills, but that doesn't mean the same person can't have both.
When we're talking about Modding we're not really talking about having to get all that technical, either. No Modder has to design their own engine or anything like that, so as long as they can find a good set of instructions on how to use the editor it's a matter of time and practise.
For the most part, editors seem to be getting easier, too (Excluding the horror that is NWN2, which you appear to need a degree in Absurdity Theory to operate), making it more likely that storytellers will be able to use them without any real technical expertise.
