Some idle wondering here. While there are plenty of excellent and successful RPGs in the sci-fi, contemporary, horror, western, cyberpunk, military, superheroes, and other genres, the big daddy of RPG gaming genres tends to be fantasy.

Why do swords and spells tend to be more popular than spaceships and lasers? Is D&D (and Pathifinder) so popular because it's fantasy? Or is fantasy so popular because D&D did that first? Or some other reason?