We use JavaFX because it is a powerful framework in java, allowing to develop client and server in the same language.

JavaFX is generally powerful, though there are some components that would require an overhaul to get fully "desktop-grade" experience with simple development (most of the pain is around management of tableview and similar components).

JavaFX is open-source and still supported, even if it could make with a more active improvement of the widgets. Still, the team maintaining it is doing a great job og steering it through the important changes ongoing on the java platform.