I agree about the extreme emergency, but my experience is that the hikers who would deploy are very poor judges of what an extreme emergency is. Being tired, hot, and hungry is not an extreme emergency, yet we see PLBs activated on a regular basis for these reasons.
People hate drones in the wilderness because we go to the wilderness to escape the noise, hustle, and bustle of urban life, People who bring noisy urban appliances into the wilderness ruin that experience for the rest of us. And they do it even though it is illegal. If it were made legal, the incidence would be much higher.