MF offerings: I can't argue, although the cutting edge MF lenses like those Zeiss Loxia that Roland mentioned are way out of my price range, and honestly my usage level. I'm more of a 1.8G kind of guy. That said, I wish that Nikon made it easier in regards to focus screens. Manual Focus was never an issue back in the days of yore with a Nikon F or Nikon FG. I was very comfortable with the split prism screen or whatever those cameras came with, and I remember getting focus pretty quick (of course I was younger and my eyes better too, so there's that...but still). Using MF with the D750 I can get the subject in focus, but it takes longer and I'm using the focus dot as well. It works, but it's cumbersome. Again, I'm a hobbyist, so these beautiful (and expensive) MF lenses are out of my realm, however as a Nikon Guy I can admit it would be cool to see them do something out of the box for a change, and some bad ass MF lenses would certainly qualify (to go with a bad ass mirrorless camera - can Nikon do it?).
Without live view, and if only focusing with a factory viewfinder, I agree MF lenses are a lot tougher. Not impossible, but not as consistent as AF.
However, with a tripod + live view (amplified for detail) = the best possible focus results with MF, esp. if you stack a couple. (It's the only way I shoot macro/landscapes.)
28/50: I like that combo a lot, although I'm currently using 28/58. I like the 58 quite a bit (although it was an indulgence), but I might go back to 50 if Nikon cranks out your 50mm f/1.2E lens. I tried all the 1.8G Primes, but I think using a 50mm prime for 20 odd years locked me in to how I see. 28mm is just wide enough, or maybe it's from using an iPhone, lol. Easier to change primes on my iPhone Plus, I have to say.
Considering that Zeiss' finest glass (the Otus) targeted the 28, 55, and 85 there has to be something to that "magic range"
When I investigate auto claims, I always bring a 28 and a 50mm.
I even tried the 28-50 AI-S zoom for awhile, to condense the two into one, but I went back to primes, just because I like using them better as well as the results better.
If I investigate a loss location, or have to photograph the remains of a larger vehicle, like a semi-truck, I will widen to 20mm.
If I am securing images of interior of a bar, or public place where something happened, I will expand to the Zeiss 15mm, especially if I want to document details (surveillance video position, etc.), its micro-detail is excellent. I always use a tripod, I always compose/focus with careful deliberation.
I would prefer slightly smaller, slightly sleeker gear than a D810/850 type size + zeiss lenses).
The AI-S lenses are perfect, size-wise, but their "dinosaur" look needs an upgrade.
I think if Nikon comes out with a sleek mirrorless line, they will be missing the boat by
not offering a new line of MF at these key focal lengths.
They could quickly rival Leica as a system (and/or the Loxia range), if they chose to, by offering their best glass in a modern, all-metal,
compact framework.
While I don't mind bulkier cameras for wildlife, for city and work I would enjoy a totally different, sleeker system ... of the same high quality.