Tobar said:

That's the other part of your reasoning I don't understand. All through out the original trilogy Vader is a very angry dude who often lashes out in violence. That does not sound like an emotionless machine.

The only thing I can figure is you're basing this all on the line, "He's more machine now than manman." But that's not the entirety of the line, the whole this is: "He's more machine now than man, twisted and evil." Again not something that describes an emotionless robot.

right...vader, even throughout the original trilogy, has moments of emotion

but also has very cold machinelike moments

but for me, a saga like this is opera, its art.

the moment when a man who shortly after practically turning his soul off has just had a large amount of his human body replaced with black wired-laden metal machinery in a dingy room by an evil dark lord who is programming him to serve the dark side...such a moment is less about wookipedia documentation of _(character)__'s precise total emotional capacity...it's much moreso an expression about the idea of losing one's humanity...becoming an empty shell.

the nuances of his remaining humanity will have plenty of chance to be developed and elucidated later on...but not here.

and even regular fully human non-dark-lord normal people like us are not always given to emotional response when it would seem humanly appropriate. sometimes even we can come off ultra cold. even as far as accuracy is concerned, just because vader is still technically capable of caring, he's also SOMETIMES incapable...just like us, but way worse.