The Java libraries are rather extensive. I would rather have too much than too little.

Static typing is a big win, particularly if you don't have to declare everything (Scala has local type inference).

Sure, there are lots of bright people using Python. But Scala is a better language and has bright users also.

If you are unfamiliar with Scala, take a look at this:

http://www.scala-lang.org/docu/files/ScalaByExample.pdf