The forms are limiting because we’re representing the wild gods. We get our power from them. You’re a bear because Ursoc wants you to represent him. You communed with him at L10 (at least you did when the quest was in the game) and he gave you his blessing. This is why you can use a bear form.
Same thing with cats, birds and goats.
I agree that we should be able to use the other wild god forms, but not any animal form.
We’ve tried Goldrinn’s form and it didn’t go so well. We got the Worgen curse and some dead Night Elves out of it. We technically can canonically turn into wolves, but Malfurion (the leader of the Druids.) has disallowed it.
It would have been the perfect time for Blizz to introduce pack form as a cat talent with BFA. Malfurion realizes that he needs to use desperate measures in his most desperate times, and uses the pack form only to find a way to control it and teach it to others. (Maybe with the help of Cenarius, or Malorne. Maybe we see him do a quest where he communes with Goldrinn himself to figure out how to calm the beast.)
It could have been a more direct damage form instead of the DoT focused form that cat is.
I also think a Tortoise form after Tortolla would have been cool. It could be a bear talent that increases your defenses, but reduces the damage you deal. That way you can choose between dealing more damage, and being more tanky depending on the content you’re doing.
But… Blizz doesn’t think like that… So… It likely won’t happen any time soon.