We see pretty much all of Vader so it’d be pretty silly to say he has a third arm
We never see what’s under the cape. It could also be a second mouth, or a third ear. I’m starting to wonder about wings.
We do see him sans cape in ESB.
the filmmakers shouldn’t feel beholden to the random assumptions of fans on the internet.
I think working with the completely reasonable assumptions is okay, though.
Well sure but in this case you’re assuming your assumption is the only reasonable assumption, which I don’t think is true.
Also, keep in mind through this discussion–Switching around Luke’s father advanced a plot point. Switching around Luke’s sister advanced a plot point. Something was gained in trade for the something that was lost. These things? Throwaway lines, as you said. Nothing was gained in exchange for the dissonance–which I’m freely admitting you did not feel.
For you nothing was gained but I don’t think for everyone. Lots of people saw the prequels. Remember the black stormtrooper outrage? That was because a lot of people though stormtroopers were clones because of the prequels. The line about a clone army was mainly to make clear that these stormtroopers were not clones, which unfortunately a not insignificant amount of the population believed.
As for the Sith line, again, if you’ve seen the prequels it would be very strange and quite “WTF” for Maz to not mention the Sith. And even if you haven’t seen the PT, for her list of dark side threats to start and end with the Empire and First Order would kind of negate the point of seeing evil “through the ages.” Two things does not a list make.