the reason why diesels aren't sold in the US is because they pollute too much. sure, they get better fuel economy, but CO2 isn't the only pollution in the world.
in fact, diesels are so common in europe, that the continent has significantly lower air quality than the US because of it. more than half of the cars there are diesel-fueled and the technology to make diesels clean enough for prime time is only today in its infancy.
the linked story doesn't talk specifically about diesel cars, but europe hasn't had any other major sources of particulate emissions in the middle of its cities for about 100 years now, since the coal-burning stoves went out of fashion in london and freed it from its "fog."
despite their higher particulate emissions, i still prefer diesels and think most other americans will too once we get used to them. they are more efficient, provide better everyday performance, and require less maintenance. also, biodiesel is easier to make than biopetrol, since most diesels can basically run on vegetable oil.
particulate emissions are only an issue if you live or drive in the city. since i have no desire to do either, this isn't a concern for me.