An AI tool gives you five colours in four seconds. They look good together. You paste them into a design system and ship. Three weeks later, support tickets arrive: people cannot read the button labels, charts are indistinguishable in print, and the brand colour disappears against the dark theme.

A button that scales slightly on hover and settles with a small overshoot tells a user the interface heard them. A loading spinner that behaves the same way says the product is still working. Motion carries meaning in an interface, and for years the only way to produce that meaning professionally was a timeline editor costing a monthly fee and a learning curve measured in months.