In my mind it depends on the terrain, climate, how likely you are to hoof it instead of waiting for rescue, and how long you might have to wait. If you want to be able to hike for several days I'd say it's a sound investment.

A tent is one item I've resisted adding to my bag. Expense is my biggest concern. My thought is that I'd be able to stay with my car or improvise adequate shelter from the Heatsheets blanket, bivvy bag, contractor bags and cordage that I do have.