We'd love to get more drivers in (and the new, much simpler protocol we just shipped will go a long way towards community-supported drivers). But we decided that having a high quality product for the people using the drivers we do support is currently much more important than having wider driver support. Once we iron out a few more quirks in the core product, adding more drivers will be really easy. But until then, more drivers will help fewer people than improvements to the core language and product.
(BTW, getting Rethink to JVM users is something I'm personally very interested in, in my case because of Clojure, but Java programmers will also benefit)
Nonetheless, I must agree that focusing on the DB itself is for the best. Keep up the excellent work.
Nashorn would let you get rid of the Javascript Protobufs implementation and use the Java library from Google, among other potential optimizations.
alex @ rethinkdb
Am I wrong in thinking that?