just a reflection of the fact that whilst everything about car design is a compromise, rear seat accommodation has a higher relative importance in the chinese market than in the west because a higher proportion of people are 'driven' rather than 'driving'.
if you want to try to use this to take the p1ss out of china, go ahead, but I don't think it furthers your argument.
other cars stretched for china only include VW Passat, maybe the Audi A6 (not sure of that one), SAIC Roewe, a version of PSA elysee and even there is a stretched chery windcloud.
Also 7 series BMW has two versions, and the 750Li variant of the BMW 7 series' single biggest market was and may still be china.