Having a payout of over 100,000 kms before taking into account the time value of $ up front is hard to justify in an era where a lot of people get new trucks every 5 years or less.
For some people the diesel doesn't need to pay-off. There is a benefit to how it drives and that's worth the cost. Extra fuel efficiency is only part of the equation.
As per Firm's comments: The Diesel is incredible; so refined, nice linear power delivery - and lots of it, just excellent.
But yeah, the emissions systems are the Achilles heel of the modern diesel.