There's this taboo of guns in fantasy, even simple true-to-period handgonnes and primitive cannons. I've seen plenty of kneejerk "GUNS? In my fantasy??" reactions to believe there's some deep aversion to the idea.

Depending on the setting this might make sense - the existence of magic can make other technologies moot. Technology may have developed differently in a fictional, magical setting. You could also argue it's a matter of stylistic choice. Maybe authors would rather have heroes swing magic swords in tense battles than simply shooting down the bad guys. 

It's just one of those controversial fantasy things, like GMs disallowing monks at their D&D tables.