The document discusses several reasons for the importance of Java, including that Java applications can run on any system due to the Java virtual machine, Java has strong IDE support to help developers, and Java is used widely in areas like Android and enterprise applications. Specifically, it notes that Java's virtual machine allows applications to run the same on all processors and operating systems, Java IDEs like Eclipse make development easier, and Java is commonly used for Android development and for integrating with other systems through APIs.