I'm not sure how Force combos would work, actually. I mean, you could turn on different Force powers at the same time in JK anyway, so what would be the point? It would make you a lot more powerful, which could unbalance the gameplay.
As to having access to all of the Force powers, I suppose that the more I think about it the more it makes sense. How you use them should determine whether your good or bad - but as the moral play has been taken out of Jedi Outcast, there's not much point to that either. As I understand it, you can do what you please with no fear (and no hope) of turning to the Dark Side.
That pretty much sux, IMO.