All of the meaning and wisdom derived from their lives was because they were alive. Now they aren't, and we don't get any more of their particular genius, and that is a damned shame.
It's also a damned shame that my grandfather, who is precisely nobody on the world stage, but still somebody, and currently in the hospital and I might get a text any minute saying he's dead, is on the brink of exiting the world, joining the hundred billion or so other humans who've ceased to exist for no good reason other than that the blind god Nature doesn't care about anything we care about. What Nature has ordained, she has ordained without reference to meaning or wisdom or the interests of those who live and die within her system, and we will be doing right when we remake her.
Reflection requires pause. It would not be the same if all those people were contemporaries of current modern scientists. In fact I have no clue how much value current scientists are adding or not adding or whether Feynman and friends would still be contributing in any way as you are assuming. The geniuses will appear after some reflection in a hundred years or so. Long after they're all gone.
I'm sorry for your eventual loss but immortality does not appeal to me the way I guess it appeals to others. Cycles in nature don't seem like a disease to me that need curing. Alleviating the pain and suffering of aging is fine and that's what these guys seem to be doing.
It's also a damned shame that my grandfather, who is precisely nobody on the world stage, but still somebody, and currently in the hospital and I might get a text any minute saying he's dead, is on the brink of exiting the world, joining the hundred billion or so other humans who've ceased to exist for no good reason other than that the blind god Nature doesn't care about anything we care about. What Nature has ordained, she has ordained without reference to meaning or wisdom or the interests of those who live and die within her system, and we will be doing right when we remake her.