Out of universe, it's because the series' lore hadn't been fleshed out yet. In-universe? Yeah, given how much of a crapsack Earth's history was after Fry became a frysickle, it's surprising.
Yeah: I'd take that.
Personally, I'd love to live long enough to go into the stars, even if it's just living on Mars for a few years.
Knowing my luck though, I'd die ten years before life-extension technology is developed. :ROFLMAO: