The other reason is that nobody knew exactly what an SUV is supposed to be at the time. You have to remember that the Q7 was the first Audi SUV, so they tried to think of cool ways to set themselves apart from the Range Rover. Glueing two V6 diesels together seemed like a good idea, especially considering TDI was interesting tech back in the day. They even installed the dirty V12 pump into the R8 supercar.
Audi CEOs would rather be burned alive then approve another V12 TDI, so the old-timer is all we're going to get. This one isn't stock, though. Instead of the usual 500 HP, it makes 575 HP thanks to a mild remap.
Acceleration isn't brutal; it takes about 5.5 seconds to reach 100 km/h. Sadly, that's slower than the current crop of fast diesel 'trucks', which include the Bentley Bentayga, the Audi SQ7 and BMW X5 M50d. But as many people point out, nothing sounds as creamy-smooth as a V12, even if it's not running on gasoline.
At face value, this Q7 looks rather ugly, and only the badges let you know it's special. It could be a collector's car in the making, like the Golf R32 or the Passat W8.