This sounds more like functional forms.
Fore me there are 3 types of forms. Structural Forms, Functional Forms, and Hybrid Forms (contains both)
Structural forms have no purpose other than to build good structure. We can look at some of the stances in these videos and see why it's important to have good structure.
To me Tai Chi forms are Structural Forms. When I do Tai Chi Fast it feels that my structure is good. When I do Tai Chi slowly, I can feel exactly where it's weak. Structural Forms position our body in the shape of the application.
When training a form or creating a form, I think it's important to set the focus of the form in one of these 3 groups.