Personally, I'm glad it's not multiplayer.
It gives TSO the competitive edge and uniqueness that isn't present in another other Sims game.
Plus I think I'd find a Sims 4 multiplayer a little overwhelming, with the extremely overly done graphics and 3D rotations. I kind of liked the simplicity of Sims originally.
The charm of TSO would never exist elsewhere. It's a unique game that can't really be mimicked properly. So, regardless of any future online game by EA, it would never be the same, whether or not it would be better.