Since an Html5 game can be supported on all these devices using their built in browsers (or a wrapper that makes the browser look like a native program), the devs decided it would be better and/or easier to create an Html5 game engine. That is all Construct has ever claimed to be and, at least for the foreseeable future, all it will be.
Since you asked specifically about Java, I have just one more point to make. Java programs are not "native" programs. They require a Java Virtual Machine (JVM) to run. A native program is compiled directly to computer language where it can be run directly. Java isn't compiled to computer language. The reason Java can run on so many different systems is because of this intermediary program. In truth, the way Construct 2 exports to different systems is exactly the same. Java has just had more years to optimize it's performance.