It is important to point out that many of those Java libraries are not pleasant to use, to the point that I once found it easier to write a basic CSV library in Clojure than to interface with any of the Java CSV libraries I could find.
It's still a significant advantage to have the option, and some of the Java libs aren't so bad.
I admit that since I am tired of Java, so far I have shied away from trying Clojure because at the end of the day, I figure I should rather try one of the other interesting languages that are completely independent of Java.
It's a shame that apparently Clojure does not run well on Android yet. If you are forced to use Java (as is the case on Android), Clojure would probably be really sweet.
Also perhaps if you are stuck in Java land, it might provide a means to escape.