The Emperor died...we saw the flare of the reactor and heard the chorus of the Dark Force get expelled and sucked back into the black hole that was his soul (ooooohhh, nice!)
Owen and Beru died...didn't you see Luke turn away, his house on fire, the two skeletons side by side? Lucas isn't subtle, he connects the dots so you can see the death.
Luke survived getting his hand cut off because you can't die simply because your hand gets cut off, especially if it is cauterized (blood vessels, soft tissue sealed off by heat) by a lightsaber. He fell a great distance but his fall was softened by the winds inside the interior of the Cloud city waste system. He lands in a great curved slide (wheeeeeeee!) and falls a couple of more feet to an antenna array (which would have effing hurt catching the back of the knees like that). Yeah he was tired and weak, probably going into shock, but he wasn't anywhere near death.
Nobody in the films, NOBODY, has ever died on screen from force lightning. Anakin gets hit by Dooku when he wasn't prepared for it and gets zapped into some rocks. Yeah he's force strong and the chosen one (so after, what, a minute?) so he gets up and fights back, strong as ever (for his age). Obi absorbs Dooku's force lightning with his saber without a blink. Yoda force absorbs Dooku's lightning and sends it right back at him which Dooku deflects, then Yoda frikkin' eats Dooku's lightning to show how bad ass he really is with the force.
Luke fights Vader and triumphs and then takes the longest force lightning hits than anyone from an untired and Dark Side strong Emperor. He can talk to his father and plead for help and after Vader tosses Palp, Luke is good to go..strong enough to drag Vader to the elevator, down some hallway, into the hangar and onto the shuttle. Vader dies from the force lightning because it destroys the suit electronics helping him maintain his life.
Mace absorbs Sidious' force lightning with some effort with his saber and forces it back upon him. When he is hit by the lightning full blast after using his hand, it hurts him, but doesn't kill him. As he is blasted up off of the balcony, you here a vocal grunt from Mace. In my opinion, Mace force jumped up and out of the way. He'd lost his saber, the lightning may have killed him (eventually), and he had Anakin to worry about also. Jedi's jumping great distances is not unusual. Jedis falling great distance is not unheard of. After being free of Sidious' force lightning, Mace's head would have cleared. He could reach out with the force to anyone of the thousands of pilots of hovercar traffic and had them in a position to grab onto their ship and take him away...
Wishful thinking on my part? Probably. I just didn't want Mace to go out that way and I think it would make the TV show that much tighter if he showed up, pissed as hell, to face armored Vader and go out in a blaze of glory like Cameron666 is writing.