The article indicates that the shelters have saved lives "dozens of times". Considering the huge number of firefighters in wilderness areas in most years, that is a small number.

While I do think that every one of those firefights should have one, for the average wilderness traveler they're fairly expensive ($300+) and bulky (~6"x6"x12").

As with most situations that can produce danger, it seems to me that you'd be best off having a What-If mentality, and maintaining vigilance regarding the conditions around you, and then acting accordingly.

And you should also have a good idea on what you should do, and where you should go, if you do find yourself suddenly in a fire area. This is an informative article by the National Wildfire Coordinating Group

Sue