Sunset
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
It's definitely not a waste of money. Like you, I always take full insurance when I rent a car in Iceland.
Here's an incident in 2013 when a French couple in a rental car were caught in a sandstorm and had to be rescued:
https://www.icelandreview.com/news/french-tourists-sandstorm-“we-thought-we-would-die”/
That icelandreview has lots of interesting stories of tourists getting into trouble, and some of their rental cars are really old and worn.