Besides, who would want to work on a stable platform where all the major library needs have been met and vetted when one can be on the bleeding edge of something new to show off?
It is nothing to be too concerned about, it is part of the normal life cycle.
Like happens to all languages before it, Java has slowly changed from a lean and sexy system into an overweight, middle-aged, sometimes nagging system that is not really much to look at. While it is great to have around, cooks great meals, and keeps the house clean, it is not attractive any more.
Nothing to be ashamed of.
Systems get older. Usually they get less attractive as they age and stop attracting people.
Java was once that lean and sexy system when compared to its contemporaries. I was there when C++ was lean and sexy compared to predecessors. I remember hearing stories about C being lean and sexy compared to needing to rewrite the program for every system.
Lots of new languages are popping up that are new and sexy. Dart and Go and Boo languages are all cute (and are mature enough that people don't look away and mumble 'tsk tsk'). Apple's new Swift language looks cute but is still a bit too young. While I have a lot of code in Java, I'm not married to the language and can use them as they appeal to me.
Now for my rambling "get off my lawn" story. Stop reading here if you don't want to listen to grandpa babble about his old conquests and drift into a drooling sleep.
I first started playing with C++ around 1985. It was so easy to create systems compared to the C systems I was also working on. I could modify behavior really easy with inheritance. I didn't need to specify my structure on every single function, just use the fancy new member functions that passed it automatically with the this pointer. Function names were much simpler, instead of the format NounVerbNoun they could be reduced to VerbNoun or just Verb. So much less typing. I didn't need to maintain tables of function pointers inside every object. I didn't need to follow every allocation with a series of intialization statements, but throw them into a constructor. I didn't need to search the entire code base and make hundreds of changes when adding something to a structure, I could just modify a single file. It was wonderful. But over time people kept adding new requirements and best practices; when you do this you also need to do five other things. Build times radically increased as features like templates were added (they were not there originally) and then huge swaths of code was automatically generated at runtime, or hundreds or even thousands of potential types were evaluated as potentially deduced types. It slowly changed from young and sexy to old and ugly.
I first started programming with Java back in the 1.1 days, around 1996. It was so easy compared to the C++ systems I was also working on. I could create a good looking graphical program that I could run from a web page in a matter of minutes, or hours at most. My first real project at the time was a distributed image processing tool, with back-end clients running on 12 machines and a coordinating server, and the whole project took less than a week. If I needed to build a similar tool in C++ at the time it would have taken five or ten times the effort. Being able to simply rely on java.net.* rather than trying to find a networking library, relying on java.awt.Image classes to process the work, and otherwise having everything instantly available made development very easy. I could dynamically build images and pass them over the web with a trivial amount of human effort.
Today I could still do that, but it would upset people. I would be asked things like "Why doesn't it use Maven to build it? Why don't I use more advanced image processing packages? Why are these talking directly with network libraries rather than using a comprehensive REST-based system? Why is there no comprehensive unit testing?" All the little additions have crept in to the process making it just as time consuming --- if not more --- than C++ was at the time I picked up Java. That makes it no longer lean and sexy, more of an overbearing source of frustration.
Finishing up my ramblings, Java has become annoying to use. There are lean, sexy, young alternatives. Java could re-invent itself to appeal to a new crowd, but I don't think it will.