Well to be honest the cheating was pretty much only done so the cars wouldn't be unbearably slow. And every other european car manufacturer basically did the same. Once the targets become impossible to reach for everyone, you start cheating.
That isn't true. It was done so they didn't have to install NOx cleaning technologies. Modern US based diesels have SCR, and EGR systems that help remove NOx and particulates from the exhaust (or prevent it from forming). However, they add thousands to the cost and complexity.
SCR systems are very expensive in modern VWs as well. Especially to repair. With the additional pressure on the engine because of restrictive exhausts engines also don't last as long. EGR systems on diesels are known to gunk up. VW used SCR systems since 2009 if you didn't know.
Yep, you have bureaucrats at the EPA pulling numbers out of their asses that become impossible to meet and still have a car that people would want or can afford. So they find a way to meet the "letter of the law" and pass the tests. Sort of like what CPAs do when they prepare your tax return.