Because it never caught on in the Java world. GUI was never as important there (plus most people already knew swing), and the rest of the framework was mostly just duplicating functionality.

I see you like this link and post it over and over, but I feel obliged to tell you this is fairly old stuff - the article talks about what later became known as JIT, which did improve Java performance a lot (and later influenced modern JavaScript engines), but never quite rose to the super-fast levels promised and hoped.