Why don't Emacs and Java get along?

I realize that may be a bit baiting, but I think it's generally true. Java dev in Emacs just isn't ideal. JDEE is stagnant and eclim works but isn't exactly top-shelf.

So my question is, why don't they mesh? Is there a technical reason that Java dev just can't be as smooth in emacs as IDEA/Eclipse/Netbeans?