A great example of this is the OpenGL API for fixed-function stuff (say, pre 2.0).
Simple glBegin, glEnd was easy to understand, but hid a lot of complexity. As new features were added (and, woefully, old calls supported and not deprecated) the API got more complicated and harder to use without trampling internal state.
APIs (usually) should be as simple as possible for most use cases, regardless of how gnarly the implementation is.
A great example of this is the OpenGL API for fixed-function stuff (say, pre 2.0).
Simple glBegin, glEnd was easy to understand, but hid a lot of complexity. As new features were added (and, woefully, old calls supported and not deprecated) the API got more complicated and harder to use without trampling internal state.
APIs (usually) should be as simple as possible for most use cases, regardless of how gnarly the implementation is.