Rogue's are crying because on paper sub is going to be a combat rogue/warrior terms of simplicity. For most of the people playing sub still it's worthy of quitting the game over if even half of this design concept goes live, due to losing what they feel is one of the last unique specs left in the game to casualization.
You'd be whining too if your spec was losing 10+ abilities like step, prep, garrote, hemo, shiv, gouge, blind, slice, rupture (gets a replacement), smoke bomb (talent), recup and shroud. IDC about recup/shroud being purged self heal mechanics are dumb and most mop mechanics like shroud/gateway are stupid anyway.
Shadowstrike, dance being passive and most of the rogue talents on the legion calculator all being passive is very anti fun. Judging from how MoP/WoD beta's went it's actually important to complain as early as possible seeing as next to nothing changed throughout the entire WoD beta where even though people were complaining it went through mostly unchanged.
Something doesn't have to be OP to have fun, people just want to have buttons to press instead of stupid passives. Even if the pvp talents/artifact talents gave us 3-4 buttons back instead of more passives left and right we'd still be losing twice as many abilities as we gained.