In my opinion, scientists shouldn't expand extend the lifespan, because expanding extending our/a lifespan doesn't mean you don't get older. You still are going to be weak, and sick. So you still can't really do anything without others' help. So, people might live in pain because they are afraid to die but still they want to die because their life is painful. Life without happiness, it is just deadly boring and painful. Even though your family is happy with you are not dead, you shouldn't be happy because you are not happy I guess...
I think this is a nihilistic, but also fairly realistic view, and I think I agree. Just because something is an advancement, doesn't mean its an improvement.