I absolutely love Stardew Valley and I do have a co op save game I play with my partner. But like others have said, it was a passion project and Concerned Ape made bank on it because A. it's a great game and his vision, not trying to just appeal to everyone everywhere and B. he fixed bugs and added (free) content. Also, multiplayer was not in the original plans and he's said his new game will not have multiplayer because of all the hassle to do it on every platform (though I bet he will bring it in, after a while, if it's possible).
I almost wish EA would make 2 games. The Sims 2/3 one that a lot of us love and still play (possibly an older demographic, but we spend money!) and the Sims 4/all ages/online social game they seem desperate to make.
