I mean, why? I'm not saying it's a bad thing, but you'd think after a while they would start developing better technology and weapons and stuff. I'd love to read about a fantasy that takes place in the industrial age, or even a western fantasy, or maybe steampunk fantasy etc. So why is it that Dwarves, Elves, Men, and other creatures rely on swords and armor when they could be discovering gun powder and making guns and trains and flying machines etc. Take my example of a western fantasy since that's what sounds intriguing to me. You can totally take a western american approach and make Elves and Dwarves similar to the Indians, the Chinese or the Irish that immigrated into the U.S (not trying to be racist, it's just an example that could go either way e.g white people being the minority) and then you would have a new frontier where traveling can be done. The gunslinger would be the new knight errant, and magic can be outlawed since its now considered "too dangerous" and with the rise of technology unnecessary and those performing it would be criminally charged and hanged (this is off the top of my head). Anyway, I think it would be great, but then people would be like "he copied Stephen King" so I don't think anyone will do it since the whole knight/gunslinger thing has been done by one of the most prominent authors. Anyway, why is fantasy always stuck in the middle ages.