"You can now do closures or first class functions" or something equally useless.
Flamebait, but I'll take it. I think the dust-up over the possibility of this being added to Java really seemed to contribute to the decline and apparent disinterest of a lot of folks (I'd really be interested in Bob Lee's opinions here, since he was someone who's ideas I was particularly aligned with at the time and has since gone pretty quiet).. That said, lack of first class functions in Java isn't a trifle. It's why Java isn't all that much fun to program in compared to more expressive languages... and a bigger problem is that more than any other language I'm familiar with Java suffers from the problem of not being able to see enough ideas in a given amount of source code. I'm explaining that terribly, but I just mean that Java code is at least 60% scaffolding that isn't material to the author's intent.
Closures, or first class functions done nicely would be a big step in alleviating that issue, IMHO.