In fact the defining characteristic of simplicity is the relevance of features. An increase in features is not mutually exclusive with simplicity. It is only when the next additional feature has no particular value to the majority of it’s intended audience that you enter into the world of confusing products.
Simplicity’s biggest obstacle is not fickle customers. It’s lazy design. It’s really hard to craft product segments based on the careful observation of people, the challenges they face and the varying different capacities they have using a product.
Everyday, I deal with the balance of simplicity and features. It is a difficult balance that requires forethought and a deep understanding of technology and business. How to keep an application as simple as possible without building in obsolescence. How to keep a handle on client demands without building unnecessary complexity. How to differentiate by adding value without sacrificing maintainability. That is the battle of the architect.