I actually agree that a lot of this came about because of the WB's request for more standalone episodes and to include Spike - not really knowing what to do with him, I think he was used for contrast with Angel and through sheer repetition of image (again, all likely unintentional on the staff's part) Spike comes away looking less conflicted. azdak had a good point somewhere in this post, about Spike being a character whose story is essentially "done," so of course he plays as less gray compared to Angel, who is still gnashing his teeth over whether or not the W&H deal was the right thing.