If Sins supports 4 cores it IS the first game ever, not even Crysis or FarCry 2 support 4 cores, its simply to hard to program and split all the operations and calculations into different cores.
Still gonna tweak around a bit more and reduce the slots capital ships take, other then that, im happy
You obviously never played Supreme Commander, which can handle up to 16 cores at once. Not very efficiently past the first 4 mind you, but it can use them all. And with a player made Core Thread tweaking utility it will use up to 8 cores very effectively.
But you're right that very few games use multiple cores effectively. But there are a few out there.