Because the defaults aren't just for convenience, the API designer is also making the parameters they think should be used the most have the least resistance. Good example is runtime parameters like in the JVM. You shouldn't start with having to tune your JVM, you probably want a middle of the road place to start with even if you know you're going to tune it.

im not opposed to good defaults, i just believe they should be explicit. The AI should read the starting.md to fill in explicitly what its JVM configuration is. Then, when you want to tune in the future its clear what options are available and what specifically is changing.