At this point in the life cycle of consoles, there's no reason for systems as powerful as ours to struggle rendering any console game at 1080p60. FC3 is not really that impressive graphically compared to other PC games that run a hell of a lot better. Crysis 2 and Battlefield 3, to name a couple. I can run BF3 at over 120fps at max settings, I should not be having to turn down graphics options in a console port just to hit 60.
I imagine this will be "fixed" in a few weeks by updated NVidia drivers, maybe a patch or two, and maybe even the DX11 renderer we were promised. Ubisoft has already shown us they can do a properly upgraded PC port in AC3, at least that one's doing a lot more to bog down the framerate than FC3 is. It's a lazy port, plain and simple.