The Java plugin was trying to give the ability to use Java, which could control all aspects of your machine, without them being able to control all those aspect

The Java plugin was trying to give the ability to use Java, which could control all aspects of your machine, without them being able to control all those aspects of your machine. I can't create a javascript that installs a C&C silently in the background, but Java by default would allow all sorts of issues as it isn't sandboxed. The Java plugin was the attempt to build a sandbox. The problems occurred because it is vastly easier to build a sandboxed language from the ground up than to sandbox a language with full access.