c.f. the Saphir Whorf conjecture, those Java programmers who know that simplified access to anonymous functions will make their lives better is by default restricted to that minority that has encountered them elsewhere. Many of these people, in my experience, would rather not be writing Java.
True enough. It just seems like it'd be disheartening to be plugging away at Java with enough foreknowledge to push through the JCP if you really wanted to be playing in a different playground.
I know and like lambda functionality and I also use Java. People pay me good money to write Java for them and I like the language and platform well enough so the chance to get closures in Java is great. At some point I'd love to use Scala or Groovy or Gosu at work but that's not the case now and I'm fine with it.