I think part of the problem was the lack of quality diesel in the US. The injector nozzles for the modern European diesels could not cope with the crap.
Please correct me if I am wrong... but I thought this was an issue until about mid-1990's?
Fuel quality can be a problem, especially if you buy from a corner station instead of a truck stop. I remember a friend of mine complaining that the repair bill for his diesel Blazer was over $500 just because he got a tank full of wet fuel. Not to mention the hassle of having it towed in, and having to rent a car until it could be fixed.
As noted, diesels have a reputation for being smelly, loud, slow, expensive to buy and expensive to fix. Not necessarily true now, but certainly true in the past. (A friend of mine described his Audi 5000 diesel as a "blender full of marbles" on a cold morning.) Fuel is significantly more expensive (around 10% more than gasoline/petrol due in large part to clean air regulations that govern things like sulfur content and heavy fractions) and currently, in order to meet emission standards, you also have to purchase "diesel exhaust fluid" (aka DEF, aka "cat (urine)"). And frankly, most people are simply not enticed by long life; the average new car buyer will only keep it for 4 years.
The case is not helped by idiots like this:
https://www.youtube.com/watch?v=6wfzUAF2X5s
I've driven some (expensive) diesel cars in Europe, and the experience is completely different. Still not likely I'd ever buy one for myself; although I understand you can get a bargain on a used "cheater" these days.
BTW, "Dieselgate" is not just limited to VW in America. From what I've been reading, regulators are finding that many other manufacturers have been selling cars that don't meet standards, even in Europe.
https://en.wikipedia.org/wiki/Diesel_emissions_scandal