It's not just Scala, it's Groovy, BeanShell, Factor (JFactor now), Fantom, Frege, Kotlin, Ceylon, Stab, Gosu, Mirah, and that's not counting all the ported versions of Ruby, Python, Lisp (Clojure) and so on.
What you haven't written a JVM language yet? It used to be you weren't a proper programmer until you'd gotten fed up and written your own CMS or web framework. Now I guess everyone has to have their own programming language.
You remove one of the major pain points of developing your own language (platform/libraries), thus reducing the costs of writing your own language, which shifts the industry to a point where there are more languages.
There was a recent survey which asked java devs which jvm languages they were taking a serious look at. Scala came out on top with groovy as the runner up. Kotlin was an also ran. Survey results:
aftershox.com/wp-content/uploads/2011/10/JVM_Survey_Responses.png
Your problem is that you think that Scala can overcome its perception problem. No, it can't. Scala is history and will never be anything. Look to Kotlin.
What you haven't written a JVM language yet? It used to be you weren't a proper programmer until you'd gotten fed up and written your own CMS or web framework. Now I guess everyone has to have their own programming language.