I think the dynamics are more complicated than that. Some diseases seriously mess with your quality of life, whether it be chemo for cancer or blood pressure medicine with nasty side effects for heart disease. Or my least favorite, a decade of Alzheimer's.

I heard the ideal death described as pretty solid health up to a very rapid decline, healthy food probably helps that.

That is not how it works. Living an additional 5 years does not make a difference; however, you "could" be living a much more productive work life, have better sex, be more friendly, be more active with your children etc...

It's like when someone says I rather smoke and die at 75 vs 80. Sure, but then you spend more time at the doctor's, you get exhaust faster, you are not always fun to be around with because your clothes may smell like cigarette and more.

It probably doesn't mean that anyway.