Thomas, that is a very good question! I'd start by saying that I really wanted to explore more scripting languages, but I didn't because I felt I would end up with chapters that had the appearance of repetition (here is an if statement in Tcl, here is an if statement in Scale, etc.).
I considered diving more into C, C++ and
Java, but really the goal was to expose someone to what was different in Linux, not how to program in specific languages.
Also, I really love Linux and there were tons of commands and features I would have loved to have included, but I kept asking myself "is this really going to help out a developer, or is this just a command I think is cool?"
Lastly, I think if I did it all over again, I'd spend some time demonstrating some IDEs. I mention them in the book, but don't provide details. Hindsight is always 20/20.
Thank you,
-Bo