The attraction of less
Removing elements can create focus, confidence and ease. It can make the intention of a product easier to understand and the experience easier to navigate.
That is valuable. But visual calm is not proof that the product is complete.
When less becomes absence
A product can be simplified beyond usefulness. Important control disappears, feedback becomes ambiguous or character is removed in the name of neutrality.
Less stops being more when the user has to supply what the product no longer provides.
When more creates value
Additional capability can reduce effort, support an important exception or make a product more trustworthy. Richness and complexity are not automatically design failures.
More is justified when its contribution is meaningful in the specific context.
The cost of complexity
Every addition asks something of the product: development, maintenance, attention, materials or learning. Those costs continue after the feature has been launched.
Complexity earns its place when the value it creates is greater than the burden it introduces.
The right amount
The better question is not whether a product should contain more or less. It is what the product needs in order to be Functionally Effective, Emotionally Attractive and Environmentally Sustainable.
The right amount is contextual. No more. No less.