I can't speculate as to why, but Nikon seemed like it gave up on the alpha market after the EDG never got a real foothold with the big three Euro brands. Not sure I can blame them for instead bringing out a killer product in the popular sub-alpha $1K class, and maintaining their strength in the entry and mid level price points. Their Monarch 5 and 7 dominate the $500 and under class among casual birders from what I've seen in the field and leading tours. Even the new Monarch ED scope is priced to compete more with a Vortex Razor than with a Kowa or Swarovski.
Clearly they are capable of producing world class sport optics as good as anything produced anywhere, by anyone. The EDG 10x32 in my possession are absolutely brilliant, as well corrected a binocular as I've ever used. I'm sure for us binocular junkies it's fun to dream of an EDG-i-fied Monarch HG, bringing the more robust build and superior glass and coatings of the EDG to the slimmer/lighter chassis and especially the wider FOV of the MHG models.
The thought of a ~700g EDG-HG 8x42 with an 8.3 degree FOV makes my heart flutter. But I am realistic that it's probably not going to happen, as Nikon seems to have all but ceded the alpha binocular market to the Euro troika.