I've yet to find a game that was improved by adding multiplayer. Coop for sure, but competitive play always makes the single player worse. Whether that's by forcing you to interact to even have a dream of achieving goals, or by eating up nearly all future dev time to balancing or online functionality. And that's without getting into the destruction of the community to sweaty try hards who make sure no fun can be had.

Heck, the Xenoblade games are coming out and proving that even MMO style RPGs are made better by removing the massive multiplayer part of it.