IMO, group participation is one of the best things about horror games and movies. I've watched some awful shit horror movies that I actually ended up enjoying because of the company I was with. Watched Rings with a couple people last weekend. Terrible movie. Would recommend.
RE8, even if it isn't co-op, should be a game that makes people want to play with company, passing the controller around and having a good mix of scares and laughs. I think that's been the real culprit of recent success of horror games. Streamers play games like Outlast and RE7 and it becomes a group activity. People want that in horror.
Of course what people want even more than that is a co-op action game. That's fine too, I guess.