I'm not saying you are defending VW but I don't think anything they did was remotely defensible.
I don't think it could be considered defensible at any level, either. But I do maintain that the market really doesn't seem to care: therefore VW are still in business which is what the parent was wondering. If you had bought a VW you really wouldn't have any reason to not keep driving it, as the end-user.
Conversely, I do think people would be absolutely furious if VW had cheated in emissions and fuel mileage tests to make their cars seem to run on very little fuel but in practise the realistic mileage would be much lower for the majority of owners. And I mean much lower than the general gap between measured and actual fuel efficiency. In that case VW might really be struggling to survive if they didn't have better technology to show the market.
Beside all the lying, which should lead to more criminal cases, there is a far more sober angle to this issue:
The vehicles were not emitting as much as specified in the papers.
This is a pretty serious offense and fineable (iirc) at up to 12.000 Euros per vehicle in Germany. (Instead, of course, car makers are allowed to give rebates only when you buy another one of their vehicles).
However, an automaker has a responsibility at a macro level because they sell so many cars.
Here's what seemed exceptional in the VW case.
1) They built cars with software that had a single purpose of misleading (lying is a more accurate term here) to regulators on their efficiency.
2) When caught they denied it.
3) When they couldn't deny it anymore they updated the software to mislead again (lying in hopes they could continue with the first lie)
4) By this point the highest levels in VW were involved.
Not meeting emissions regulations may not be a big deal for everyone but it impacts others and it has direct impact on others.
I'm not saying you are defending VW but I don't think anything they did was remotely defensible.