Personally, I don't care whether it has MP or not, as the singleplayer will be focused on RPing my Shep wherever his choices take him. However, I'm just a bit unsure as to how exactly it will work when everyone is pausing to choose commands at least once every second, if not more often. This problem persists even in a co-op-esque setup, where both you and your co-op partner will both require access to the command wheel to choose powers, switch guns, switch types of ammo, etc.
One possible fix is: You play through a level in singleplayer, and then the game takes that playthrough of Shep & runs through the actions you took during that level. You and your co-op partner are Shep's two squadmates, with Shep's orders to you reduced to "Squadmate, do something to this unit, I'm *power*ing that unit!" However, you and your partner don't get the command menu, only hotkeys.
This sidesteps the problem of extreme choppiness while players vy for control of the command wheel, while keeping one player from feeling like a fifth wheel. It also allows players to try on different types of gameplay (e.g. Liara's Adept to Ashley's Soldier or Garrus' Infiltrator) in a variety of settings and scenarios.