> The biggest current knock against Java I see is JNI, which unlike the core language is absolutely horrible.

JNI was only ever designed to be good enough, and it is. The new FFM API aims to replace JNI in most cases, but it's designed to be "perfect". As a result, the new API took many years to develop, but JNI was quick to develop.

It would be nice to have the FFM API much sooner, but alternatives like JNR and JNA have been around for a long time. There wasn't a rush to develop a JNI replacement.