Ah nice find Tanooki, I didn't even notice some items were exclusive to the Full Party capsule. I am honestly not against the thought of having really exclusive items into the game. I would honestly be happy enough if they raised the probability of the overall capsule to 10%, while keeping the drop rate of those really exclusive items the same. That way, it won't be too bad to keep spinning for these exclusive items, as you are still winning parts in the process. Depending on how (un)lucky you are, you might even complete some sets before winning the exclusive. That is already much better than winning just a few random parts.
As far as I see, none of them are that necessary to complete a set and are more like nice complementary items to them. For now, it's only weapons and generic faces that are kinda replaceable by other parts. I think it would only get really bad if they made necessary parts of a specific set into an exclusive, so let's hope that won't be the case.