People who would like to use Clojure or Scale aren't fans of Java. And if you aren't a fan of Java, chances are good that you aren't a fan of the JVM, too.
I'm already using something else. Why should I use the Java eco-system?
I don't see why this should be. It sounds a bit irrational. From my perspective, Java is an iffy language and Java programs are often nightmarish to read. But the JVM? I see no reason why my feelings about Java and its culture should color my opinion of the JVM. The JVM is a technical marvel. It runs Ruby faster than Ruby with far less effort. It supports a whole host of very different languages, many of them quite good. And it's just blazing fast (modulo startup speed).
There are other valid choices, of course, and the JVM is obviously not the optimal choice for every project, but I think it's fallacious to rag on the JVM just because its most popular language isn't to your taste.
I gained most of my expertise about the JVM running Ruby apps on it with JRuby (and after that, Clojure). I started out something of a Java-hater and eventually came around to kind of sort of liking Java (although I'd certainly rather write Ruby in the overwhelming majority of cases)
I'm already using something else. Why should I use the Java eco-system?