What we in the USA are wondering is not why they aren't being mass produced, but why they aren't being supplied to the USA at all. Even if only the largest dealers (B&H, Adorama) chose to stock them, I'm sure they'd sell a good number of units. It's really hard to believe that the market is substantially better in, for example, Britain, but then it is true that Bushnell never distributed its WA 30x eyepiece for the Elite scopes in the USA--they were only for the European market. And several US bicycle companies make excellent commuter bikes that they do not sell in the USA. I don't understand marketing. It must be forbidden for US dealers to import these Nikon items (Nikon Fieldscope eyepieces, EII binoculars) because otherwise I'd think the big ones would offer them (grey market?).
--AP