This is a subject that is near and dear to my heart.
I need to emphasize to all of you "Anti-Auto-Everything" guys out there that I am one of you! I grew up in photography with all manual cameras in the 1970s...Up until a few years ago I was still using an all manual Hasselblad film camera when I decided to chuck it all in...But I couldn't stay away...The siren call of the DSLR was singing.
I was using cameras bought in the 1970s until 1996 when I bought an A2E more or less by chance(I didn't know the difference between A2E and A2...A2E cost $100 dollars more...Hmm must be better lol)...This was my first experience with Auto-Focus and I just thought they all did that(eye control).
As I have gotten older, my eyesight is not what it was when I was 17...I found manual focus to be harder as the years passed...When lighting was not good I was missing focus as often as I was nailing it(with 35mm, not with the Hassy, which was still easy to focus, with the magnifier, for static subjects)...But for moving subjects auto-focus really helped me out...And eye control makes the chore of choosing the focus-point much easier.
I can't count how many threads I've read about choosing FPs and focusing and recomposing with all of their associated difficulties. I'm always thinking "Man if they just had eye control!
Please note that "Eye controlled focus point selection" is NOT the same as "Auto focus point selection" where the camera chooses what to focus on.
With Eye-control it really is a simple matter of just looking at the part of the subject you wish to be in best focus and shoot...That's it...No thoughts about which focus point to choose(with densely packed focusing points this can be daunting)...No focusing and recomposing...That is it!(And the camera did NOT choose what to focus on...YOU did.)
As a brother "Anti-Auto-Everything" guy I wouldn't even consider using "Green Rectangle" mode or any other "Auto-Everything" mode...I don't trust the camera to make shutter-speed and aperture decisions for me and certainly not ISO or what to focus on. If I were shooting a race car on a track, for example, and wanted the front bumper to be in focus with focus receding to to rear, I could simply choose shutter speed and aperture to accomplish this then look at the front bumper through the viewfinder and shoot. NOTHING automatic, I chose EVERYTHING, INCLUDING focus point, just by looking at it, not fumbling around trying to find the right focus point by pushing buttons or turning dials, or by focusing and recomposing.
Eye-Controlled focus point selection I have found to be a seriously useful professional tool and I think it worthy of your consideration(If Canon will give you a chance to try it on a DSLR).
Thanks to kfreels for starting this thread!