I adore Jack, but he always was kind of dark IMO.
Oh yes, which is why I like that quote right from the beginning.

The doctor has the distance to make moral absolutes; Jack doesn't.
That's a good way of phrasing it. And the Doctor isn't human, that has a lot to do with it I think.

He's made a lot of "wrong bloody calls" or however Spike phrased it-- I'm a work of course and no time to look it up!
That's pretty spot-on, and yes, that's an excellent parallel.