I think BMW right now is sending out recall letters to Diesel owners for a "software update" to "remove a left-over function which may increase acoustic harshness".
All jokes aside, I think everyone is too quick to blame the manufacturers, it's not entirely their fault. There are lots of factors at play here, there is obviously a misunderstanding of the capabilities of the technology on the part of the legislators, and a lack of sufficient development time. There are still quite a lot of flaws internally to the diesel engine, and no amount of exhaust emissions devices will fix that either. It is a common misconception that a diesel charge ignites instantly upon compression, which is not at all how common rail direct injection systems work (which is by the way, the reason why diesels have so much torque, even just 20 years ago, diesel engines in passenger cars had nowhere near the power of their gasoline counterparts). The fuel is ignited as it sprays outwards from the fuel injector into the combustion chamber. However, the fuel only ignites at the front of this spray beam (which is why diesel injections are pulsed during the injection period, and not continuous like gasoline engines). NOx and PM aren't inherent to the fuel itself, but to the way the charge behaves in the combustion chamber. This wave of fuel propagates outwards, eventually reaching the piston crown where it turns to follow the curvature, eventually, multiple flame fronts meet, and compete for the oxygen available at their intersection, which generates particular matter. Conversely, this flame front pushes excess oxygen behind itself, generating NOx. Volvo has recently invented a new piston, for use in their semi truck engines, that solves this problem. The piston crown has wavy bumps that deflect the flame fronts away from other each other, more evenly burning the charge and drastically reducing PM and NOx. Automotive diesels would need something like this. Combined with WOT propane-injection, Diesels could become mad clean beasts.
Another angle to blame are the people themselves (myself included, and everyone reading this). The manufacturers are responding to market forces, they do what the public wants. What does the public want? Power and fuel economy. Let me ask you this then, for 99% of cars, which are used as daily drivers or driven to the shops etc. Why the hell do you need power? In every country except Germany, there are speed limits, and I've driven in Germany, and people doing 200km/h+ are the rare exception (I admit to have been in that exception). Most people keep it around 130-140. Which again means, you don't need power. Diesel engines aren't the only thing becoming dirtier. Small turbo petrol engines also have similar issues with emissions, where they do fine in tests but fail when driving in the real world. This is a global problem with people, not manufacturers. Horsepower doesn't matter for a daily driver, what really matters are fuel economy and emissions. You don't need an ML63 AMG with optional offroad package to pickup the groceries. If people wanted to solve the problem of pollution, we would have done so already, but people only want to shift blame onto someone else. Don't get me wrong, I love powerful engines, I love supercars, I love the M120 engine, but that love has a time and a place. Manufacturers know perfectly that you can only chose 2 out of the 3, power, economy, emissions. So they chose power and economy, and pretended to chose emissions because people pretend they care about the environment (and by extensions, themselves). Is it deceptive they did so? Sure, but the real deception is happening in front of your mirror. It shouldn't be plaintiffs v. Daimler, it should be plaintiffs v. the 8 billion dumbasses that live on this planet.
Or we could move on from diesel engines to homogeneous charge compression ignition engines, which is what people who like diesel engines REALLY like, they just don't know it yet because the technology isn't out yet. It combines homogeneous charge spark ignition from gasoline engines with stratified charge compression ignition from diesels, or in simple terms, it's the best of both worlds, or in different terms, it's the only option where we get to chose 3 out of 3.
People deceive themselves all the time, my favorite example being electric car owners in a location where electricity is produce by a dirty means (like burning coal), that's a classic example of shifting the blame.