You're right, I don't suppose I would want to be somewhere it would take an ambulance half an hour to get to. By googling a little, I found the Aberdeen Fire Dep't annual report. Their average EMS response time in the City of Aberdeen is 4.5 minutes. I also found a news story about the rescue of a swimmer at Ocean Shores where the responders arrived within two minutes!
I've no idea of the capabilities of the local hospital. I would guess that for any kind of major medical stuff (e.g. heart surgery or joint replacement), you probably have to go to Seattle even today, which is about what I would expect in a county with a population of under 75,000 people. Off duty EMS staff do a considerable amount of work transporting people to hospitals in Seattle, Tacoma or Olympia. My HMO's nearest clinic is in Olympia so I will have to travel for checkups and eyeglasses anyway. Maybe if Ocean Shores becomes an in-state retirement Mecca, they will open a branch there. But I think Sequim has probably beaten them to the punch on that one.
You have given me something to think about.