Ya, I didn't realize the accessories differed either, but I always planned to get both anyway so it didn't affect me and left me with a surprise. Unfortunately for some, each has cool stuff the other doesn't, so it's not like you get most of the cool stuff with any one figure. I think the spear is actually my favorite, the way he holds the shuriken doesn't seem natural, though it works, and with no wire in it, the whip isn't exciting, but the spear works great for the post they made him in.
As for the articulation, I think part of that is because the right arm is hollowed out for the wrist blades to retract, which is cool, I didn't expect that on sucha small figure, and they probably figured it'd be more aggrivating to have an articulated left arm and no right than to just not articulate either.