I guess as often happens with drivers aids threads we are each putting our 'marmite' opinions. Either love it or hate it.
I accept some may find the Jazz ACC might not be as good as they had on their "Audi Doody" or whatever. (BTW There is no Audi Doody ,its my attempt at Humour based on the old American colloquial greeting "Howdy Doody"
) VAG cars for instance may use radar/lidar detectors that perform better in rain and fog. I can see potential advantages of a system that can 'see' further than a human in fog/heavy rain ,but does it then go beyond where a human can see well enough to supervise it? If so it becomes a 'driverless car' using technology thats not yet adequate for that role. Equipped cars may be travelling much faster than human controlled cars. Maybe their drivers will go one step further with hands off the wheel, dozing or concentrating on phones etc. I dont see that the ability to set basic CC so the car can travel at speed through poor or deteriorating/fluctuating weather without any detection is an advantage.
Supervising ACC does require some effort and learning its foibles. Maybe more than you can learn in 4 or 5 attempts. I learned to work 'with 'it. Indeed in heavy traffic I find it less 'work' to switch it off and drive ,manually. So I agree there is room for improvement. I find traffic around SE UK is often too heavy to use it much. But on long hauls on quiet to moderately busy motorways I find it a welcome 'assistant'.
