I think to some degree it's because unless Polaris has some substantial architectural improvements and NV only releases something that amounts to a die shrink that the mid-range NV part is going to have the performance advantage.
Even if you're an AMD fan you'd want them to release something more powerful.
No, why? This is nothing but good news in terms of medium term competition.
For starters it makes it clear that AMD have a sane, coherent strategy to produce an entire top to bottom line up of 14nm cards, and on a sane time scale.
A real relief. They've been doing all sorts of odd things since 20nm fell through and might have continued.
They absolutely need to do a total top to bottom stack refresh, so they release the bottomish bits of it first, sell them at a bit of premium for the first ~12 months. The power efficiency should allow that.
Then once the rest of the line up rolls out these cards can drop down to form their low/mid end for the 2-3 years until we get the next die shrink. At worst that's enough competition to keep NV plausibly honest.
In all honesty, they should probably get a bit of market share back. Stuff like simply having a plausibly competitive notebook GPU can't help but be useful.