Maybe people who don't care how trendy the language is? There are thousands of well tested, well maintained libraries for java mainly because of the funding from the corporate world.

What was the first API for amazon aws in? Java. Nearly everything has Java API because it is so well supported.

Java developers don't get off on, programming language one upmanship. Some people like being boring...

SAP? Jave API. Oracle? Java APIs. Google Stuff? Java APIs. Android? Java APIs

nearly every piece of commercial software has java apis.

I remember having to use a 3rd party django paypal plugin and it was half broken(IPN callbacks), that would be unlikely with Java. Ended up faffing about in its source code to get it working.

Good point. Sometimes I ask myself why everyone thinks that Ruby Gems are so amazing. I've had all kinds of awesome Java Libs for years that work without much problems.

Maven obviously isn't as nice as the way Ruby handles Gems, but to me it feels more structured.

As far as I know, you could use those APIs with any JVM language, not just Java. There's Clojure, Scala, Groovy, Jython, JRuby and probably a few others.

True; but for random programmer off the street, these languages impose an additional cognitive load. For a given Java library, most of the example code and documentation will be geared to Java itself, and translating that to "another JVM language" isn't always trivial.

Especially since most programmers out there are not polyglots, work in a big company, and may not even by "programmers" but just "engineer/accountant/business person who programs a bit".

Many people do.

What is the business value for rewriting the code in the flavor of the month language?

In what sense does it improve profit?