Just aiming for length rather than quality of life may not be the best idea, but usually people aiming for a long life are also aiming to be healthy as long as possible.
At least if you're alive, you've probably got the option to end it if you make that decision, but once you're dead that's it (not allowing for reincarnation).
I like the idea of healthspan instead of lifespan. I’m happy to keep going as long I’m healthy. When the good times are over and everyday is “please end me” day, I hope I don’t linger for too long.