Let's face it: Blizzard is doing the right thing by removing, replacing and/or merging certain abilities from the game time to time.
Ability pruning serves the need to free up action bar space and make room for potential new abilities to be added in the future.
Many of you who are shouting at Blizz for an oversimplified game seem to forget that Blizzard is actually aiming to create 36 unique "classes" with specs just now in Legion.
The exact opposite to the 11 more or less streamlined classes we have now.
Are you aware that many removed spells will be available to you in the form of class- or maybe even spec specific tomes and toys which teach you the spell?
This is what an RPG should be about. Exploring and expanding your abilities and spellbooks - Blizzard is doing a fantastic job with this in Legion.
I am certain, that going forward into the next expansions, Legion serves to create the room in the action bars for more and more spec specific abilities which fit just the exact fantasy niche players are craving for.
TL;DR
This pruning is just the first step towards spec specific abilities in future expansions guys.