That's just because they were quick demos.
F3 supports packages and imports as in Java. So you can divide your application into as many separate files as you like.
The F3 interpreter actually loads F3 classes by means of the Java class loader. So to deploy F3 code you simply archive it in JAR files as in Java and then make such archives accessible to the Java class loader.
Our F3 IDE plugins are also closely integrated with the corresponding Java plugins. There is no special F3 "perspective" or F3 project type. In both Netbeans and Eclipse, you simply use normal Java projects, create packages using the existing Java facilities and then create F3 files in those packages. The normal build process will "do the right thing" and archive your F3 code into the output jar file of your project.