It’s not often we are hearing from publishers, devs and other people that a single player campaign (“SPC” from now on) are like a leech in terms of content and budget. Cliffy B said it cost like 75% of the total budget of a game, and BunnyHop made a well made video-article about SPC. I think that video gives you enough context.
….games with a SPC usually gives them a soul to back up.
There are lot of examples about games without a proper SPC, like Evolve, Titanfall, Star Wars Battlefront, and Rainbow 6: Siege. Without further ado, you can see that these kind of games doesn’t last too much on shelves, being Titanfall an excellent example of what happened some months later, with EA trying to force the consumers to buy it with USD $1 and a free Season Pass.
While the can entertain, the problem with these kind of games is they have no soul to rely on. Humans tend to care of things even if they are inanimate machines, and good SPC can be, as the dictionary says, the essential element or part of something.
I’m not a psychologist to properly understand what humans feel, or rather, how they feel to a product made for the sole purpose of entertain, being that a game, a toy or a movie. But I can assure games with a SPC usually gives them a soul to back up, giving the user a sense of careness for what it presents to him (or her). It's like the Art Direction of a game: it can be entertaining to play but if the game’s graphics feel shallow, the player will care less for the world it is presenting, and that means he will care less for the game itself.
Of course some decades ago there was games oriented to a multiplayer only experience, like Mario Kart, Unreal Tournament or Quake III Arena. Look closely and you will note that most of them are from well established franchises. Other ones were made to replace their soul for what a couch experience could make, or they were fucking astounding enough to define or create a genre, like MOBAs.
In a world where now games are being bound to online-only experiences, the soul of an SPC are nowhere to be found, so players don’t care months after because they don’t feel nothing about it, replacing it with the next AAA game scheduled for launch. If your game doesn’t define a genre, or doesn’t expand over a world-known franchise, just put a SPC and pray it's good enough to keep players coming to the multiplayer part of the game. Ask the devs of Call of Duty 4: Modern Warfare if you want any advice on that — That game defined the modern multiplayer with a well done movie-like single player experience.
People want something to care. In Star Wars Battlefront, I could care about expanding some of its universe, or rather somebody expanding it through his/her experiences. You don’t need 40 hours of SPC content, all you need is a good well made story even if it lands below the 4 hours.
For those that still doesn’t get the idea: give the players something to care, something human to the game, and they will come again even years after. You can dispose of any sweeter on your wardrobe, but you can’t if that sweeter was a gift of your grandmother.
My point is: Humans doesn’t care for other humans until they can feel they have a soul, even if its a fake one below the surface.