zlep: As Lukin86 mentioned, there's no mouse support in any of these Lego games, not even the most recent ones like Lego Batman 3 or Lego Marvel Superheroes.
I think you're over-reacting a bit to call it unplayable (although I agree entirely that they *should* support mouse). If you find you just can't get used to the two-handed keyboard routine, a controller works well with the Lego games (not surprisingly, since it's probably console-focus that has generated such long-term mouse-blindness in the devs).
Actually, the first two Lego Star Wars let the player use the mouse to play. I think it was movement or something.