Now that I'm awake, I'll explain.
If building NPCs was really a form of play, then getting your whole group to do it with you would be a viable idea. Turns out, people don't think spending a session just making NPCs is a good idea so I submit it shouldn't be considered a form of play.
D&D is a highly flexible game system so naturally it'll attract a wide variety of people with a wide variety of gaming taste. Perhaps the OP will have better luck with a more homogeneous game/player culture???