DEF works but DEF adds cost to an already expensive powertrain system. For this reason, and many more, that's why we're paying more for goods and services since the vast majority of transport equipment and harvest equipment uses +75hp diesel engines.
We did a study at work a while back. We have a GMC pickup and a Ram pickup. Ram is gas, GMC is diesel. We had to deliver a piece of equipment to Indianapolis, and chose to use the GMC because it's a little more fuel efficient. Not a month later, we found out that we had to go BACK to Indianapolis to pick that machine up (repo) so to study, I took the ram.
The ram is a little less expensive to make the same exact trip. Why? Diesel costs more, maintenance & repair costs more, and then you add DEF into that. A box of DEF is about $25 now locally including tax.
That same trip in the ram ends up about $110 less expensive if you figure it all in. So with that said, we're going to keep the GMC another year (it's coming up on 5 years old) and it will be sold, and not replaced with another diesel-powered vehicle. Probably just keep the ram.
Note that they are both the same exact truck, 2500 series no frills, only real difference is one is a duramax and the other is a 6.4. Rear gearing is nearly the same, tires nearly the same, pulls the same trailer, etc.
Emissions stuff has always been a good thing, but has always cost consumers a little bit of money to implement it. That also means a boost in tax income for the man.