Torque3D, the engine the game is based on, has pretty poor lighting effects. I don't think this would work very well without moving to another game engine.
Doesn't the game already uses a "barely" Torque3D engine due to how much it has been modified? Cant it be modified a bit further to get better lightning? Just like what SOL did to AC?
I mean, when you are talking about rewriting a major portion of the lighting engine, it's not exactly modifying it a 'bit'. This is more or less the same reason we don't have splitscreen yet, because it is possible, but it would require rewriting large portions of code from scratch for a feature that isn't really worth the time investment. Beam team really like to kill several birds with one stone, so this probably won't happen unless something drastic happens.