Snapper...
You may be right...I don't know. I do know that I didn't "get" it until I shot manual to see how one affected the other and after I realized that all AV or TV was doing was turning my dials for me and that the only difference was now that I wasn't fully in the drivers seat...I saw no reason to not turn them myself.
You could be right...I don't know.
I'm making a short video (uploading now) to explain how to adjust the T2i SS/Aperture/ISO to create a proper exposure.