I've never been a big fan of dev's making these holiday special events in games unless it's tied into the storyline. As you and Morado said it takes a lot of time away from working on the actual plot of the games, and I'd argue a few games would already be finished if their devs didn't spend several months a year working on multiple holiday specials. Also most devs never even release their holiday special in time.
If you could tie in the story of a character to a holiday, you should totally do it. Like with Sabrina's story, totally gives you Halloween vibes and you could've worked it into the story (like her first attempt at summoning demons was being done on October 31). But if you don't want to add any holiday events ever, 99% of the players won't care. You're making a quality game that even most of these AAA game companies can't (or won't) put out. And that's what is most important part.
