I often come across posts where people are discussing the logic of a movie or comic book. An example could be Star Wars, where they discuss how a light saber works. Or which superheroes would win in a fight against each other. To me, it seems pointless to discuss such things as it is fiction. Just an insight into someone else’s imagination.
A lot of science fiction has to put some emphasis into world building because it is how they create the settings in which their stories work. The setting is narratively important in a way that it isn’t for a medical drama since the audience can’t backfill seeing information from their personal knowledge base. The Tommy Westphall Universe was presented as a critique of this requirement as, if you followed crossovers, most of American television occurs in the head of Tommy Westphall.
So why is it important how pretend worlds work? Well, it creates a place for stories and plot to exist without the baggage of reality. It also creates interesting implications for how we view our own world. For instance, the transporter issues in Star Trek have spawned a lot of conversations on personhood in the wake of copying things. It also becomes a way to talk about ethical issues before technology catches up to create an ethical issue.
Some of it is fluff, but there are interesting ideas being discussed within the worlds we make.