Animation is a huge topic all to itself and I would love to see a dedicated forum for it.
I suppose we could add a category for animation, if there is enough interest. That said, animation in 2D and animation in 3D are often different beasts, which might confuse things if we have a dedicated animation category. For example, 3D animation is often bone-based, while 2D animation is often sprite/frame based. Additionally, GUI-based animation is often different than 2D game animation, despite both of them being in 2D.
That said, we do have an animation tag. You could place the topic in the dimension you are animating in and add the animation tag. Personally, placing the topic in the specific category the animation is in (2D, 3D, GUI, etc) and adding the animation tag seems like the ideal solution. That way, there is little confusion on what dimension and purpose the animation has, while still showing it is for animation. That said, others may view it differently and that's fair.
I do appreciate the suggestion, and if there is enough interest, we can certainly look into adding an animation category on the forums.
Edit: Also, I assumed when said "topic" you mean category