I find the idea of immortality horrifying. People would become ridiculously risk adverse because they could live forever as long as they didn't have an accident. Imagine the sort of repressive policies those voters would support in order to remove risk.

I also think for society to evolve older generations need to die off. Peoples worldview becomes partially fixed in their youth, and for some it is entirely fixed in their youth. I wouldn't want to live with a bunch of geriatrics from the 1800's.