Sounds like you haven't ventured off road much FirstToy. Not doggin' ya for that.
You might want to check the dictionary on the word "defective". I never used that word (are you voting for Kerry?)

Kidding, stick with me......
It's a known fact in the industry that Traction Control systems are a poor substitute for "traction" (or having lockers) off road. They've been dogged for years and it even took me many trips in the 100 to convince 80-owners that Traction Control (if done right) can work, even in tough situations.
The problem is FirstToy that the traction control in the 4Runner/GX and almost every other vehicle made today is of poor design and/or a different design. They allow too much wheel spin which is hard on the rig and the trail, they cut power which results in the stop of forward motion, and they simply don't get the truck where it needs to go. Most systems are meant to help in snow, rain, and mild rocky terrain. For that, your 4Runner is as good as anything out there. This doesn't mean they're DEFECTIVE systems though they are flawed for serious off-roading. I am guessing it costs more $$z to make a better system like on the 100. Who knows??? If not, there's no excuse for these other rigs to be designed less effectively.
To date, I only know of 3 rigs that have traction control done "right" for off-road driving. They are:
2000+ Land Cruiser
Discovery II
Range Rover/New Range Rover
The Rover's however in some years have a flaw. They didn't have a CDL-Traction Control combo and therefore were inneffective and/or dangerous in certain situations. For more on this go to:
http://www.expeditionswest.com/vehicles/ewvehicles/Land_Rover_Discovery/index.html
(see the lower part)
As for 4Wheelers' 4Runner comments, they've also commented the GX spun wheels too much at times which was not good. It depends on where they took the things. For mild 4Wheeling you're fine. For more challenging, you're not. Sorry to tell you that. Until you locker-up a GX or 4Runner forget the serious stuff. Come on down to Tucson and we'll run!
BTW: You brought up VSC? It has nothing to do with ActiveTrac and off-roading (unless you're sliding around corners on dirt roads at 50MPH). VSC works great on the 100 as it does on almost EVERY vehicle that has it. VSC is easily tuned on truck or car.