It's good because it's not a direct allegory. I do read it as a bit analagous to our current situation: a fight for our lives against a relentless enemy which has vague complaints against us, but who should have gotten over it a long time ago. The bad guys always have a point of view, but it's clear that the cylons are bad guys, with the exceptions of those with pangs of conscience. Lots of discussion of the nature of religion. All very good stuff without Hollywood telling us what we should think about it.
Well they didn't quite just "cast" him like to shut him up. They approached him, from what I've read, more as a peace offering.
To-may-to, to-mah-to.
They do the big thing that good sci-fi does: they ask questions without providing answers. Sci-fi isn't about telling the audience what you think, but helping them figure out what they think.
Keep in mind that without Hatch spending a lot of the last 20 years insisting BSG still had legs there probably wouldn't be a new show. It's good to give him a few bucks for his efforts.