"There's almost no excuse not to use Scala if you're deploying on the JVM."

There's a good reason, actually - library maturity, especially when trying to get data in and out. Try and do some inner joins with typesafe slick and you'll know what I mean when you see the SQL it generates.

Or try and use Play Framework's json de/serialization, and be prepared to punch your monitor in the face.

I think these critical libraries can get there, but the lack of resources on these projects has me thinking we'll be waiting awhile.