The studio screwed this movie over.
First of all, they told the director to tone down the violence for a PG-13 rating, which really took away a lot of the impact. This movie was spectacular but imagine how wildly crowdpleasing and amazing it would have been to add good-old-fashioned gore. I have no problem with horror films being PG-13 (despite what most people think, gore just doesn't fit in with some horror movies and audiences just want it unnecessarily forced in), but slashers should NEVER be toned down for a PG-13.
When it is blatantly obvious that a film is limiting itself and cutting away from the most exciting moments in an unnatural way just to achieve a PG-13 rating, it really hurts the film. Gore can really set the tone for a movie and impact/emphasize the entire viewing experience. Luckily, there were many other elements that helped carry out this film, but some bloody sequences would have definitely made a perfect viewing experience.
And in the end, there was absolutely ZERO point in toning down this film for a wider audience because it didn't even get a wide theatrical release. This film didn't benefit in any way from its PG-13 rating and it actually held the film back from being a 100% satisfying experience.
Even if it was released theatrically, I don't think it would have benefitted from a PG-13 rating. R-rated horror is hot right now. And I don't think younger audiences would be able to truly appreciate this film as an homage and satire of the slasher genre. And I think that younger audiences don't quite "get" horror comedies and just want a serious, generic horror movie that is "scary". Tweens and teens go to horror movies to be scared and feel rebellious, and I doubt that many would be satisfied with a movie that focused on other elements that didn't involve cheap scares.
This film deserved a wide release. Even with a PG-13 rating. The effort, skill, production values, and effects immensely exceed that of any horror film this year. After all the work and money that was put into this film (this looks like a $20-$30 million production), the studio truly screwed this one over, which is sadly happening more frequently with horror films thanks to stupid-ass VOD and such. I'm surprised, but grateful that Krampus got a wide release because these days, horror films have to fall under a certain criteria to be released theatrically. And that criteria usually is bland and generic.