I think the hardest part about actors/actresses getting older or dying is that it is a reminder of our own passing lives and mortality. I know I always get a little upset when I see an actor for whom I haven't seen since I was younger and they look so much older. Or even someone you see all the time and just don't realize how much they have aged. For example, a few months back I was watching a news story about Alec Baldwin's custody battle. He looked older...Until my wife put on Knot's Landing. And he was on the show. It was from 1984. It was just bizarre. How much different he looked. And just the other day. I was watching Star Trek 2 and then saw Shatner in Boston Legal.
There's only one actor I'd bring back, turn back time about 20 years, and return him to the prime of his life - and that's Christopher Reeve. He left us way too early.
When I was younger, I had a crush on Pamyln Ferdin (voice of Fern in Charlotte's Web, voice of Lucy in some charlie brown cartoons, Paul Lynde's daughter in his show in the 70s, starred in Star Trek TOS way back....) I believe she's an animal advocate now. Anyway, I would mind seeing her come back to do something.
BTW I googled and emailed her a few years back, and she wrote me a very nice response.