The topic I think speaks for itself, but here's a bit more info:
I'm on my 2nd CFI, well advanced in the curriculum. I'm not comfortable with power-on stalls. My 1st CFI only served to scare the crap out of me on all stalls, I had no understanding of even why do them...how stupid is this, who would do this on purpose, keep the darned airspeed up and the AoA down and you don't stall, seems simple, why do we keep doing this crap every friggin flight, are you wasting my money...[rant off]
I am responding without having read the entire thread.. forgive me if my post is redundant.
Why do we do stalls? Well.. thats what we do when we land.. and what we try NOT to do when we take off..
Think of a power off stall (or, more appropriately termed as an "approach stall") as a landing.. when you come in to land, your power is off, and you are holding off the ground, pulling back gradually until the plane stalls.. but since you are only a foot or so off the ground, it mushes onto the landing surface instead of mushing then breaking and descending in a stall.
A good scenario to wrap this around is about making a power off approach into a field and then having to go around in the flare without ever touching the ground (fouled runway, etc..).. (or coming up short on a power off approach).... doing a stall allows you to get experience with mushy controls and arresting descent without descending into an obstruction, plane, ditch, etc.
Thats also why during your recovery you try not to descend through your target altitude, because that would represent "hitting the ground"...
Now.. power on stalls.. with full throttle power and heavy right rudder, can give you one heck of an unsettling sight picture and deck angle if you aren't accustomed to it. Why the heck would we do such a thing?
Well.. if you botch a short field/max performance takeoff and over-rotate you could experience a power on stall, and the goal is to recognize and recover without hitting the trees or sinking back to the ground in an attitude not conducive to landing. Power on stalls can be termed "departure stalls" as one common place to experience them is on a departure profile at low airspeed.
Thats why you try very very hard to not lose altitude during the recovery, and you get practice handling the plane with mushy controls, pi$$ poor forward view, AND torque/P-factor from the maxed out powerplant.
You will need to demonstrate competence in both approach and departure stalls to get your license, because that competence is what keeps you alive and hopefully from making a big mistake when you have the misfortune of a small mistake or small surprise on takeoff or landing.
You are practicing these maneuvers at altitude so that sinking through the goal/minimum altitude isn't complicated by bent metal and medical bills.
You should expect to do power on and power off stalls, slow flight and steep turns for EVERY FAA checkride and rental check-out flight you ever do in your flying career... The higher your license, the tighter the tolerances or higher the bar when performing those maneuvers.
Here is an example of what a stall and spin too close to the ground to recover look like....
http://www.youtube.com/watch?v=BI9SjKT-oWM&feature=related
and another
http://en.wikipedia.org/wiki/File:LSO_vs_F7U_Cutlass.jpg
Both are from carrier flight decks, but much of the physics (minus the p-factor) are the same as what a primary trainer would encounter.