We can measure a design on a scale from frustration to delight. The middle of this scale is a neutral point, where the design is neither frustrating nor delightful. It doesn’t suck, but it’s not remarkable either. It’s just a neutral experience.
When improving a bad design, we first must remove the frustrating bits to get to that neutral point. Observation of the users’ experience, followed by careful rethinking of the design can remove everything that’s introducing frustration.
Improving the design from the neutral point, to introduce delight is a different process. It’s additive, whereas getting to the neutral point is reductive. We have to know what to add to make the experience become delightful.