Campaign versus multiplayer assets. There's nothing happening really in those shots. Whereas you have to account for 8-24 players in multiplayer, a myriad of weapons and vehicles and maintaining 60fps.
Just imagine though, what campaign spaces could have looked like, had they said we should stick to 60fps for multiplayer, but do locked 30fps for campaign.
I do think the dev maps look really good though. I mean Overgrowth is definitely a looker, maps like Plaza definitely ooze visual appeal. The only issue is we haven't really gotten any dev created outdoors spaces aside from Forge or Warzone. I want a map using the colors and look of Reunion/Genesis etc. I need that water, that skybox, the visual art in an arena map.
It's not the mp graphics that people complain about ... It's the art direction...
There are scenes in the single player campaign that are every bit as chaotic as MP can be, but they take place in playspaces that are much more appealing to the eye...