Development always involves searching for the optimal solution. Doing nothing would lead to stagnation and, consequently, a step backward. Anyone can criticize what's bad.
The disadvantage of the VR principle, although not manifesting as knocking, also applies to diesel engines. Ideally, a spherical combustion chamber would still be the best option!
However, the spherical shape is only optimal when everything else is right. The Chrysler HEMI hemispherical cylinder heads are also just seen as a small step, and unfortunately, they aren't much more effective.
The Passat BM is also about achieving the stated fuel consumption with a current vehicle. We've discussed so many times what factors influence that. Just look at the weight (equipment) difference between your car and the BM. Then borrow a BMW and drive at a constant speed of 75 km/h. You'll see that even it can do less than 5.1 liters per 100 km, because even my old ASZ Golf manages significantly less than 4.9 liters per 100 km with that kind of driving in the not-so-flat Sauerland region... but whatever.
I believe there are several reasons why a VR TDI engine hasn't appeared, but primarily, as always, it's likely due to cost and the fact that relatively small 4-cylinder engines can now cover a wide range of power outputs.
My BMR can be driven very gently and still achieve a fuel consumption of 4.7 liters per 100 kilometers.
Driving on a country road through the Hunsrück (a Rhenish slate mountain range), he achieves a speed of 5.3.
Driving the Blue is a matter of the driver - and the others, because if they annoy me, I just drive away.
I'm not sure what you mean by "Lustisch." Could you please provide more context or clarify your request?
Coincidentally, I was able to give a VW salesperson a summary of my experience with my Passat last week, and I mentioned that it's a shame there won't be a VR6 TDI.
He was very surprised, because it seemed like he had been waiting for that to happen...