It was probably created to help shake any stigma that Sigma is a lesser brand than Canon/Nikon. Sometimes you need flagship products like that to sell everything else, even if not practical (like Chevy does with the Corvette).
Same thing as hydro pneumatic suspension on Citroens, or variable strength air bags... :-(
would love to see some interesting feature on the canon flagship. 'interesting' as in a little out there and eye control would do it! as would having focus points over the entire sensor area, or a sensor which uses more of the imaging circle (think square, round, cross shaped!)...I could go on!