Death can often be a very slow process.

Sometimes it will cause a worker (and the worker's company) to be less efficient due to health-related issues. Not to mention that caregivers (e.g., family) may also be less efficient by taking time off from work or quitting work all together.

Sometimes people will be put on disability for health reasons before they should need to retire. This is a drag on the welfare system and (often) the economy if they had been a productive member of the workforce.

There is also a potential quality of life issue (both present and expected), but that's not as easy to measure as the previous points. It also has some potentially complex implications that are beyond the scope of this post.