Tinker is the racial identity class of Goblins and Gnomes. It exists because they needed a way to fight physically to make up for how small they are, and frankly they shouldn’t have access physical strength classes like warrior for the same reason. As for other races, they have no need for what tinker offers because they aren’t small. And beyond not being a technologically-minded race in the first place, Vulpera aren’t Warcraft so the less they get the better.
You could maybe open it up to like… the dwarf variants. But the class being gnome/goblin only would not be a negative.
Goblins/Gnomes not having Tinker all this time is like if Night Elves were playable and Druid didn’t exist, and you know for a fact nobody would be ok with that.