I’ve noticed that, broadly speaking, there are two approaches to speculative fiction–leave the mechanics of the world vague and mystical (see: Star Wars and Lord of the Rings) or explain in some detail how the systems of the universe work (see: Star Trek and Harry Potter). Since Bionicle shifted from the first approach to the second as time went on, I thought you might have a unique perspective on this. What would say say are the benefits/drawbacks of each approach, and which do you prefer personally?
I tend to prefer the latter, because I like world-building. The former certainly leaves more room for fan fiction, etc., but that can’t be your first consideration when working on an IP. Also keep in mind, though, that a lot of the world-building associated with BIONICLE wasn’t so much in the published work as it was in my answers to questions online.