I think this is a matter of a person's comfort level in the wilderness. For me, who typically hikes and always backpacks alone, a communication device is not a necessity. But it sure makes me feel a lot more comfortable. And that makes me enjoy the wilderness more.
There is another advantage to these devices: much more freedom in the wilderness. Because I am alone 95% of the time I am out there, I am confined to the flight plan I give my wife each time I leave. If I see a route that looks interesting but is off the flight plan, I have to forget about taking it, because if I get into trouble, I won't be where I said I would be.
But with a PLB, for example, I can go wherever I want because if something goes wrong, I know I will be found quickly.
As for sprained ankles, these are not necessarily trivial injuries. The first and only time I went sking I got all my ankle tendons torn and it completely immobilized me. The doctor told me that I would have had less pain if I had broken my ankle. I am still a little skeptical about that report but the point is sprained ankles can bring you to a complete halt just like a fracture.
Also, wasn't that last SAR extraction from the VW a female who was LOST? I don't think they went in because she had a sprained ankle.
