One things that comes to my mind is: when I was starting using Python, I was eager to mock Java people and their absurd approach (write everything in Java, specify a full classpath for all dependency, etc). I pointed out as it was easy and quick to program in Python rather than in Java.

I did not appreciate what the pros of a linear and well-defined (by the language) approach to the dependencies, and a clear API between the system libraries (java, javax) vs the user libraries, actually gives A LOT of value. Even though it's more cumbersome to use.