OP's question is impossible to answer and the variety of answers provided show that different circumstances have different results.

Only you know exactly what your particular policies cover and only you can see if what the cruise line or third-party vendor has to offer is worth it.

Just because a policy covers air evacuation, does that mean evacuation to the closest point in the US or your hometown? If overseas, is it evacuation to a major city or back to the USA? What about the costs of people in your travel party. If your spouse is stuck for 30 days at a hotel, not wanting to leave you alone, are you covered for that?

As to the basics of missed cruises and the like, take a look at what you are covered for already. Maybe you bought a package including air and ground transfers which covers the cost of getting you to the next stop. Maybe the next stop is a $75 flight. Maybe it's $7,500.

The one thing I would do is make sure that you focus more on medical than on anything else. That is where the costs can be extraordinary. Whether you get stuck for a $15 taxi because you missed a van is hardly the sort of thing to freak about.