- They want a MILC camera
- They already own lots of Nikon F mount lenses
This thread is populated with people who failed to answer your question.
Rather than tell you why
someone might want a Nikon MILC camera, they are instead telling you why they
personally prefer DSLRs. They are telling you how much they dislike EVFs, or some other aspect of the mirrorless design, but not telling you why "someone else might want a Nikon MILC camera."
Obviously, if someone really dislikes MILC cameras they will not buy one from Nikon or from anyone else. We already know that lots of Nikon users bought Nikon 1 cameras. And many also purchased adapters so they could use their existing Nikon lenses with it, and still get AF ability.
Doesn't it make sense that some Nikon users, (specifically, those who WANT a MILC camera), would leap on a Nikon MILC system that is BETTER than the Nikon 1 was?
If you doubt this, then think about all of the Sony and Olympus DSLR users who bought into Sony and Olympus MILC cameras because they could use their existing DSLR lenses with adapters and still get full automation. The only difference for Nikon is their potential market of "users with DSLR lenses" is much larger. So they could potentially sell more of their own MILC cameras to them. And it sure beats losing those customers to a competitor.
It just makes too much business sense for Nikon to neglect these users, and continue to let them migrate to Sony E, Sony FE, Fuji X, or M4/3. The handwriting is on the wall. The mirrorless market share is slowly growing and the DSLR market share is slowly shrinking. In terms of BOTH market share and revenue.

Since CIPA started keeping separate MILC statistics, the MILC market share has doubled from 18% of the ILC market to 38%. And MILC revenue share has grown even more. This market cannot be ignored. And full frame MILC has the most profit potential.
Nikon will introduce Nikon Z for all the same reasons they introduced Nikon 1. Except this time, they will have a better product with much broader appeal.
Obviously, DSLRs still outsell MILC cameras by almost 2 to 1. But it isn't 4 to 1 any more, and it would be foolish for any major manufacturer to not be in BOTH markets.
The folks at Nikon are pretty smart people. They see how much success Canon has had with their EOS M system, and they are kicking themselves for not being in that market. It is hard to deny that this makes sense for Nikon, and will be a good thing for Nikon users who want to move to, or add a MILC system. A no brainer.
It may not be the right product for all the DSLR lovers who have filled this thread up, but it will be an important option for many others. And it sure beats having them migrate to competitors.
One final point.... around a year ago I posted a poll on the M4/3 forum asking
"If you migrated to M4/3 from a DSLR, which brand did you migrate from?" Over 200 Dpreview members replied, which is a fairly large response for these polls.
Almost 30% of the M4/3 users who previously used DSLRs came from Nikon F mount. I bet Nikon was aware of this too.
--
Marty
http://www.fluidr.com/photos/marty4650/sets/72157606210120132
http://www.flickr.com/photos/marty4650/sets/72157606210120132/show/
my blog:
http://marty4650.blogspot.com/