I've never done WFA but I imagine it is FA with an emphasis on extended care and evacuation. What did you expect in 15 hours?
If you take a WFR course (80hr) you will learn a lot more about improvised care with available and natural means because they have time to teach it to you!
What you need is about where you go, when you go, how long you, what you do, and who you do it with.
Three people on an 8 day backpacking trip above treeline in class III terrain probably need a different kit than a pair of folks doing an overnight in the foothils.
I've become convinced that a short length of 1 or 1/2" webbing, a crevat (triangular bandage, a clothes pin, and an adjustable length trekking pole wrapped with duct tape are the bare minimum critical pieces for improvising splints/slings/traction splints (a length of 3" coban is pretty critical too). Cordellete isn't a bad idea. There are so many things you can improvize into splints: trekking poles, platypus/camelback, pack stays, sticks, ice axes, paddles, skis, tripods, potty trowels, etc etc etc. Nevertheless, I often carry a SAM. You don't have to. If you don't do you really carry the equipment necessary to improvise and do you really practice enough to be confident that you can improvise? For example, I know that right now I can quickly and effectively build a femur traction splint with:
1 length of webbing
1 extendable trekking pole
1 of any of the following: a shirt, long johns, webbing, crevat, roller gauze, cordelette
Without some webbing or cordelette, I'd pretty much guarantee that you aren't carrying enough duct tape to improvise a litter. Maybe you don't need to because you don't have enough people or a slope/rope to move one. If you do, the litter can mean being able to move your buddy to a safer drier warmer more managable shelter to await rescue (or can mean the difference between self rescue and no self rescue for your group).
My medical/survival/repair kit all together weighs in around 1 pound and it is essentially what I carry as my personal kit on SAR missions too. That is not going to suit someone with a 5lbs base pack weight. Than again, someone who has a 5lbs base pack weight is *most* likely not doing the terrain/activities that I am. That's OK. I carry it because I know that the extra weight means that I can effect extra care and survival that are more likely in my AO. That's what I need.
Nobody is suggesting that you carry 5lbs of medical gear.
"I felt like the two most important things were left out of the course: 1) learning how to get out of the woods if you're lost and 2) learning how to make shelter with no/minimal materials."
-That is in the realm of a survival or orienteering course, not a first aid course. They didn't even have time to teach you much improvised care.