$35k a year is a lot if you don't have any income - at a 4% withdrawal rate that requires an additional $875k in savings to cover, and at most incomes it takes many years to save up that much (plus obviously all the years you work to save 1.5M for your $60k/year or whatever in living expenses).

There is also the fact of a 10% or however much copay, which will be a lot over time if you get a chronic illness (which would also reduce your ability to go back to work).

Additionally, most people expect healthcare costs to rise with age, so will want a buffer on top of what healthcare currently costs to cover future bigger expenses.