The interface of an application is not decoration. Every design decision has a measurable impact on how people use it and the results it generates.
There is a common perception that interface design is an aesthetic matter: whether it looks good or not. That leads to design being the last thing invested in and the first thing cut.
The problem is that interface design is not decoration. It is the layer where everything that matters happens.
How design affects user behavior
Every design decision — where a button is, what text it has, what size it occupies — influences whether the user does what we expect them to do.
A form with too many fields reduces the submission rate. A checkout process with confusing steps increases abandonment. A cluttered management screen causes users to make more errors and take longer to complete tasks.
None of this is subjective. All of it is measurable.
The cost of a poorly designed interface
In internal applications, a poorly designed interface reduces team productivity every day they use it. In customer-facing tools, it drives away users who would otherwise have completed their objective.
The cost is not only financial. It is also the time the support team spends explaining how something works that should be self-evident.
When it makes sense to invest in design
Diagram: emotional design cycle
Redesigning something that already exists is always more expensive than designing it well the first time.
