I'm curious why you'd divert from the historically compelling example of the Blues and the Greens.

I strongly associate the Greens with, well, the Greens -- a set of political parties in Europe and the whole environmentalist movement.

Blue is a politically-associated color in the US as well.

The part of politics that's generally fun for people is putting forth an impassioned defense of some idea or policy.

True, but LW is VERY unrepresentative sample :-) and maybe we could do a bit better. You're right in that discussing the "pros and cons" of ideological positions is not a good idea, but putting "Warning: mindkill" signs around a huge area of reality and saying "we just don't go there" doesn't look appealing either.