As the title states, please bring back pet spec as an option.
Aside from some of the specs making no sense whatsoever, like Stags being Tenacity instead of Cunning, the current model of having pet families locked into specific specs often forces the player to give up their preferred pet model to gain access to the preferred spec passive.
If you want to get ambitious, introduce a training system for Hunters that allows the player to teach a preferred pet a special ability from another pet family. If a player loves using a Raptor, but would rather be able to snare an enemy than apply mortal strike, let the player tame a Bird of Prey to help train the Raptor, replacing Savage Rend with Talon Rend.