I think that a large part of this "step change" in system pricing is because the expected sales volume allows the development cost to be spread over a larger number of units. If you also consider that the basic command station technology has now been around for some time, the established manufacturers can afford to sell the "design element" of it more cheaply since the development has already been paid for. That just leaves the cost of designing the graphic touch screen interface. Since ESU have already done this work for Maerklin/Trix, their own unit and now Bachmann, the number of units which will pay for it increases and the price drops accordingly.
As has been said not a few times recently, it will be interesting to see what Lenz announce at the Nuremburg toy fair.