So this is more from the perspective of aesthetics, but it also has gameplay implications.
Firstly, we now have Dark Ranger Hero Talents, so there is no reason to further stain the MM spec tree with any dark abilities. It’s now a disruptive outlier anyway, and “Sentinel” class tree talents were removed as well. Not to mention the inappropriate combination of Wailing Arrow with Sentinel Hero talents.
Secondly, the currently intended implementation of Wailing Arrow is clearly not meant as a proper on-demand CC, but rather generally as a powerful (rng) shot with some extra value, so there’s no reason to stick to Wailing Arrow specifically.
Thirdly, the corresponding part of the MM spec tree is already working with wind theme (wind arrows), so (something like) Windburst would make a perfect fit there, with neutral theme, high damage and a bit of utility.
Fourthly, Windburst specifically is a nice example how to give Hunter shots some needed party/raid utility 
