Design systems sold us a specific promise: define the components once, apply them everywhere, and the product becomes coherent. The promise was real. Consistency reduces cognitive load. Familiar patterns lower the barrier to learning. A well-applied design system genuinely makes products more usable. But something got lost in the execution, and it took a decade to notice what it was.
The problem isn't consistency — it's the conflation of consistency with sameness. A great jazz ensemble is consistent: the musicians share a key, a time signature, a tradition. But they don't play the same notes at the same time. The coherence comes from shared constraints, not identical expression. When design systems enforce identical expression — the same button radius everywhere, the same spacing tokens applied mechanically — they produce the product equivalent of a band that can only play in unison. Technically correct. Emotionally flat.
What Consistency Actually Means
Consistency, properly understood, is about predictability of behavior and legibility of intent — not visual uniformity. A user should be able to predict what a button does from its appearance. They shouldn't need every button on every screen to look identical. The moment consistency becomes a goal in itself rather than a means to legibility, it starts working against the product.
The most engaging products have always understood this. They establish a grammar — a set of rules governing how elements relate — and then use that grammar expressively. The rules exist to be played with, not to foreclose play. Figma's marketing site, early Stripe, the best Apple product pages: all deeply coherent, none pixel-identical. The coherence is felt, not measured.
"A design system should be a vocabulary, not a script. Vocabulary lets you say what you mean. A script tells you what to say."
What to Reach For Instead
The alternative isn't inconsistency. It's expressive coherence — a design that has a strong point of view, uses deliberate variation to create emphasis and rhythm, and treats the design system as a starting point rather than a ceiling. This requires more judgment than applying tokens mechanically. It also requires giving designers room to exercise that judgment, rather than treating any deviation from the system as a regression.
The best design systems I've seen leave deliberate blank space — places where the system gives principles rather than components, where the designer is expected to interpret rather than implement. This is harder to document and harder to audit. It's also the difference between a product that users recognize and one they remember. Recognition is table stakes. Memory is brand.