Don't confuse "development" with "maintenance". They are very different things. We see most of those projects merely being maintained, not radically improved.
True development is happening within the Haskell community, for instance, where they're taking concepts from various fields of mathematics and applying them to software development in ways that haven't really been done before.
Most Java-based projects are merely reimplementing something that somebody else has already done, or they're making minor, incremental improvements to a well-aged piece of software.
Anyway, I'm not arguing that Java is the most active in this regard, just that this particular criticism - of all the ones one could level - is, in my humble opinion, relatively weak.