The reason that I've chosen to develop in JavaFX Script is that it runs on the JVM and leverages the power of Java (it can instantiate, and call the methods of, any of the millions of Java classes that exist today or tomorrow.
Another reason is the simple and elegant declarative scripting, that among other things, allows you to put layout components in the UI containment hierarchy. See the first in a series of tutorials that I'm writing for Sun on compiled JavaFX Script for an example of this declarative scripting:
Thanks,<br />James L. (Jim) Weaver<br /><a href="http://JavaFXpert.com" target="_blank" rel="nofollow">"Helping you become a JavaFXpert" weblog</a>
WHAT is your favorite color? Blue, no yellow, ahhhhhhh! Tiny ad:
Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop