The monitoring panel beeped frequently and for no reason, the lights seeming to serve only as steady reminders of his vulnerability. His electrical systems were woefully delicate, and he was forced to protect his vital chest panel when dueling. This system was so vulnerable that Antinnis Tremayne was once able to deactivate Vader's entire suit by pressing one button on his chest control plate.
The suit, and more specifically the helmet, use some high technology for the interface. But the chest control panel is made of huge lights and big freaking switches, just like if it was salvaged from an archaeological museum. It was even replaced on at least two occasions, but its odd design was globally kept.
Why incorporate such patent weakness to the armor? And why would Vader tolerate it?