I don't know what field these languages are "taking by storm" -- it certainly isn't the field of corporate software development.
Java and C# have the following advantages:
- Familiarity, which means programmers are easy to hire and can finish projects without overcoming a learning curve
- A huge amount of high-quality libraries for almost any task
- Good IDEs and build tools
- The concepts are not exotic. The object-oriented features are now the industry standard.
Nobody wants to spend the time to learn these new languages if they don't offer a significant improvement over Java and C#. Of the ones you listed, Scala is the most likely to succeed because it can interoperate smoothly with Java and offers concurrency features that Java does not. Twitter's successful use of Scala has also contributed to the language's popularity.
Java and C# have the following advantages:
- Familiarity, which means programmers are easy to hire and can finish projects without overcoming a learning curve
- A huge amount of high-quality libraries for almost any task
- Good IDEs and build tools
- The concepts are not exotic. The object-oriented features are now the industry standard.
Nobody wants to spend the time to learn these new languages if they don't offer a significant improvement over Java and C#. Of the ones you listed, Scala is the most likely to succeed because it can interoperate smoothly with Java and offers concurrency features that Java does not. Twitter's successful use of Scala has also contributed to the language's popularity.