I have found a huge difference in the quality of an image that was retouched from a RAW and saved as a JPG from an image that was retouched from a JPG and saved back as a JPG. After experimenting with this, I no longer retouch images from JPG. If the JPG that the camera produces it good, I don't mind using it, so I agree with you on the AWB, but try looking at the difference between retouching a RAW and a JPG, I think this exercise may help improve your results.
I said tweak, not retouch. By tweak I meant tasks such as: discard ones I don't want, crop some, maybe slight exposure adjustment. I'm doing this directly in iPhoto, it needs to take less than a few seconds per photo. Anyway, I'd agree with your technical points, but my point was TIME. I don't have the luxury to spend hours every time I need to sit down to transfer some event photos to a web album where other people can download them. If I did this professionally, or was retired or something and had lots of time, I certainly would shoot everything in RAW and make every photo a work of art in Photoshop. And yes, adjusting color temperature on a JPEG produces worse results, this is an argument for having better AWB in the camera in the first place!
People seem to really like what I offer (for free), I enjoy shooting, and was willing to spend the money on a "pro" camera to capture really good shots. The camera and lenses are truly phenomenal and I've captured some great moments with them.
The question was about what I'd like to see improved in the 5DmIII. One of my biggest problems has been interior existing light situations (I find flash distracts kids). Anecdotally, I'd say the problem has gotten worse with the proliferation of cheap CF bulbs in the marketplace. Most interior places are becoming a disaster in terms of variations of lighting sources and color temperatures etc. I realize this is a really tough nut for Canon to crack, but improved AWB would allow me to shoot better photos in the camera and not have to spend time at the computer.
I guess I distinguish between "taking" photos and "making" them. When my intent is to make photos, I'll shoot RAW and spend time at the computer perfecting images. A lot of the time, I just need to "take" the best photos I can in the first place, and get them out to people in a hurry. Improved AWB would help do that. All I'm saying.