And please explain why that is?
Battlefield as a franchise has been predominantly a multiplayer experience, therefore most of its fan base is multiplayer oriented. Naturally, the studio is going to concentrate on that aspect more-so than the single player.
Historically when DICE has done single player as part of Battlefield they simply weren't long enough or good enough. I believe personally they are wasting time and resources on something that not a lot of players will experience.
There are a lot of reasons why their single player attempts have sucked or not sucked. It can be from budget, resources, time, etc...
I'm not saying it's impossible, or it can't be done. It's that they have tried quite a few times and failed. Either bolster the team and try to do an amazing Single Player and Multiplayer or drop one and concentrate on something you are good at and where majority of your audience is at.
I think only a few games have handled FPS Single Player and Multiplayer that is good, and that's HALO. I think Resistance 2 was good as well. There are probably a few others, but not much. Also, I just want to add, most of the Single Player FPS games do the same shit, go here in the world do this mission, then go to the other part of the world, a set piece here and set piece there, the way they do it, it just sucks. They need to do something new and different rather than the traditional approach of failed single player.
Again, not an impossible, but either take it seriously or don't even bother with it. I haven't played any of the Battlefield single player experience, same goes for Call of Duty except Call of Duty 4: Modern Warfare because it was actually decent.