Part of it is also that on the average most people in the United States are much fatter than the rest of the world, and thus NEED bigger vehicles. Also, for some reason, people here still seem to think that bigger = safer.
Mostly it comes down to the fact that the average person in the US is much less educated when it comes to vehicles than people in Europe.
As to the VW truck, I wouldn't be surprised to see it make its way here soon. They're already trying to get in on the GIANT SUV market with the Atlas, so I can see them bringing the pickup here at some point.
Well, "educated" in terms of vehicles is partly true, I suppose, but I think it's more about different needs and values. I've lived and worked in Europe (Germany) and the culture around cars is very different. In the USA, the way cities are laid out, their relative youth, and the ways cars have deeply shaped the experience of most citizens in the past fifty to 100 years means our take on cars is a lot different from people whose cities and living patterns were largely determined long before the automobile came about.
So, American preferences for big vehicles that are more spaces than machines makes sense if you look at the history of our society and our communities. Personally, I hate it, but I'm pretty much one of only maybe two or three people I know in my circle of colleagues and such who actually likes driving per se. Most everyone I know views driving as a waste of time between things you really want to do, and views cars as appliances whose only task is to get you from A to B. Which again makes sense when in the USA you have to use a car to do pretty much anything. In that sort of situation, people tend to see only the utility of cars, not their entertainment value. And as a part of that, they don't care enough to research stuff and figure out the real data behind things like safety and what not.