I personally think that the moral decisions in games is good, however very unbalanced. Generally the Evil path is far simpler and usually have very little consequences. In Fable 2 for example, if your evil, and you go around killing everyone you see, you actually get a ton more XP, then someone playing Good.
I think the most Balanced Morality system so far is Fallout 3( however still a bit evil biased). If they Balanced it out, and gave more sever consequences to Evil Characters, and as stated above, make it more of a spectrum, then a Binary value, then it would enhance games dramatically.