Remember there are two different scenarios here. First is inland, second is coastal/offshore.

Most PSKs seem to be aimed at the first scenario; freshwater (possibly costal) I can see it being aimed as a suppliment to trapping/hunting. Someone once said the there is not enough calorie content in trout for subsistance. If I was going to be in one place long enough to rely on this a food source, fish traps (rocks, planted spikes, basket type) would be the way to go as they don't require tending. As for the PSK, getting through the initial stages of long term survival or as an alternate source of food seems to be adequate justification. The hooks can also be used in bird snares.

Persons adrift in life rafts (Baileys in the Pacific) have subsisted on fish/turtles they caught. Bait/Light/Luck has alot to do with it. Coastal survival is similar, but can be supplimented with trapping/hunting. With both of these, the primary catch is saltwater, and can therefore be eaten raw if necessary. Hence all overwater/shipboard/liferaft survival kits should contain a significant fishing kit.

In either case I personally would not want to hook into a large (say 8-10 lb) catfish or salmon with a handline.