Why do they feel the need to prolong life and nature?

Idk I think human cloning would be a cool scientific discovery but its a horrible idea if your trying to live forever(in a way but the clone wouldn't actually be you) or if you trying to make a dead love one come back(cloning thier cells but it wouldn't be them) its a horrible idea but we could use cloning to clone an arm if someone got theirs cut off so they can get a cloned arm reattached it would be good if we use it for people who need it(aka: in any major accidents)