If you've ever driven a k-car, you would know that the car needs to be floored before it gets anywhere. My Ford Tempo and Toyota Corolla both run the engine at about 1200rpm then downshift as soon as the gas pedal is touched. The only reason the Tempo didn't jerk when doing it was because the transmission was broken; the car could accelerate while holding a constant rpm. When the transmission isn't broken and actually has fixed gear ratios with no slipping, the car jerks. The automatic is doing the equivalent of changing from gear 4 to gear 2 without rev matching. It just slams the clutchs in and the engine speed doubles or triples in the blink of an eye. None of this happens if the gears can be locked, which is a feature most modern automatic transmissions are capable of.
Slowing down is fun as well. The car tries to gear down while applying the brakes but it sucks at doing this and the car lurches because of it. When doing the 3 to 2 shift, engine rpm goes from 2000 (third gear) down to 1000 (neutral idle speed) then it jumps up to 3000 (second gear). I'm sure that isn't hard on the transmission at all :awe:
Here is a brief description of how your automatic transmission is trying to seppuku itself:
http://www.autos.ca/auto-tech/vehicle-safety/when-to-shift-an-automatic-transmission-manually
An automatic transmission in the sport shift mode never unlocks the torque converter, so manually locking the gears is ideal.