OFOTD.
Basically your argument falls short as Nagra is foremost targeting a professional market.
There are a number of radio organisations in Europe that stems back to the old national radio monopolys. One example is the BBC of England, in my part of the world it is the Swedish Radio. These typically used to have quite hefty budgets and worked with a technical department selecting and maintaing equipment used by the "field" people. For these people, one really important aspect of the pricing issue is that equipment that stops working far from home is extremely expensive. So reliability is a very large point of the price parameter. Add to this that discount pricing typically shaves quite a bit of the list prices for these organisations. And add to that the ratios between prices between different manufacturers when it comes to the list prices in Europe for Nagra is different from in the US.
Now, a professional organisation generally never buys things from specs only. The organisation takes home a number of copies of the machine and tests them several weeks in real world situations before committing to upgrading the whole fleet of machines. I believe several of the Nagra offerings are made to fit this situation.
Next exemple: I had the pleasure of taking a very, very small part in making a commercial ad for one or another coffee brand (or whatever). It featured one of our countries best known opera singers. Filmed on location as well as sound recorded in a studio. About 35 professionals in the crew (add some 20 amateurs including me pressing buttons on a Bassoon). The mobile power supply for lighting came on a full size lorry, they had several lamps each on 5kW each (think garbage bin size) (not directly seen in the movie). Now, the lone sound guy would never get another job if for some reason his equipment would fail due to him taking short-cuts. In this case he did run a SD 744T on location.
one version can be seen on this page a bit down
http://www.resume.se/nyheter/2010/10/06/fler-ovantade-besok/ Next example: John Willett has a long history of making commercial CD recordings of classical music. After very careful listening and actual testing of machines he has choosen the Nagra VI as his standard machine. Your choice will probably be different as your requirements differ.
Of course, most of us are not in the same category. And maybe the ML4 is made to a completely different market, it might be something one large customer has requested. Good marketing in its larger sense is to know your customer and produce what the customer is willing to pay for. And our part of it as customers is to carefully choose exactly what fits our situation.
Given all this, I did buy a 722 for my own private money several years ago and use it quite often.
// Gunnar