Possibly because Vader by design is meant to be intimidating?

"No. Although it does exist." And was something Vader may have designed if he wasn't sure Palpatine would see it as an invitation to 'test' it's capabilities. "It can control heart rate, speed and depth of respirations, deliver corrective cardiac shocks, monitor blood glucose and correct it, and monitor for infections and if programmed and equipped to do so deliver infection fighting medications." That last was a large "if" as he had a port in hugs collarbone for that.