Because it's simply more painful to do many things that should be trivial. I have about 8 years of java under my belt and I rarely use it anymore (only a few times in the last 3 years). Instead I use one of those trendier languages... all of which you list are long past the possibility of being only a trend.

There are definitely some great reasons to use java for certain tasks, specifically due to the wide range of library support. If I had to use Java for a greenfield project though I'd probably take a serious look at groovy.