Perhaps the primary goal of Nautilus as a product is to sell other B&W speakers. It is so extraordinary and easy to remember that it can be the reason for people to choose a pair of normal looking and affordable speakers from B&W. Nautilus was for sure how I have first encountered B&W.
It's a show of engineering prowess. It's like Nikon's f0.95/50mm lens. Almost perfect, but impractical for most.
Moreover, these kind of show pieces allow technology creep to lower levels, allowing the know-how to practically improve other products down the road. I think it's necessary to have products like these.
A similar product could be produced reasonably cost effectively with injection molded plastics and doing the unit adapted crossover in digital domain. I think it has not been done because the story of it being painstakingly manually crafter, the tower of monoblock amplifiers needed and even the high price itself are the allure of this kind of product. Just like the selling point of a high end wristwatch is not about its capability to accurately tell time.
Another important part is that the speaker itself is only a part of the overall acoustic system, the room that it is placed within forming the other part, equally capable of changing the sound. Very few people have the luxury of designing the listening room with as much consideration for acoustic performance as the speakers have.
The thing is, even the performance comes close, injection molded plastics won't have the same characteristics of the tuned fiberglass body with the tuned filling material.
Also, to be able to create the same crossovers in the digital domain, you'd have to go pretty high end again, because, passing through a single DAC at the end of the chain is not same as a DAC -> ADC -> Crossover -> DAC chain at the end of the day.
All in all, you'll come pretty close but you won't be able to create the exact same device at the end. Also, some stuff's (like good drivers built in small numbers) price doesn't come down that easily.
Yes, dedication and tuning of a special room with 8x 500W mono amplifiers requires a hefty sum and these speakers are may not be expensive when all the price is factored in, but throwing in modern plastics and a couple of DSPs cannot replicate all that, all the time.
A bit like the Bugatti Veyron. When it first came out it was explained that several companies had been trying to build this mythical car (1000HP, 400Km/h, trying to stick F1-like performance in an easy to drive "consumer" car) and all failed.
Then VW decided they'd buy the brand and do whatever it takes to make it work, result being that it's sold at a loss. Even at a million bucks. According to Wikipedia the production cost is 5 million and "Volkswagen designed the car merely as a technical exercise"
