Neonchameleon
Legend
I don't think it's an issue of mechanical complexity. It's more that story creation via Premise & Resolution is not as intuitive as "You are the hero. What do you do?". Sim only requires actor-stance, while Narrativism I think requires at least occasional author-stance. And the idea of both playing a character and authoring part of the character's story is not particularly intuitive.
I actually think pure Storygames, where all the players/storycreators are always in author-stance, are a more intuitive enterprise. Most people have no trouble with the concept of round-robin storytelling. I think Nar RPGs are a tougher idea to grok.
Pretty much this. The barrier for entry isn't complications - it's a conceptual shift. Once you've jumped over that hurdle and absorbed it the rules aren't a problem - it's the stance between actor and director (or possibly throwing in some author in there) that's the problem. Pure actor stance (as trad RPGs often are) or any other pure stance is much easier.