Which do you care more about: it works, or it looks good? There's a reason Java became such a big platform for business applications and it isn't because it cared about fashion fads.
Can you name another very popular and very good looking Swing application?
Even if you can, you can count them on one hand. Swing was a massive failure, and rightfully so, because Swing/JavaFX apps look, and more importantly, feel, like a broken mess.
In contrast, SWT/JFace apps look a lot more native and feel extremely snappy. Apps build on the Eclipse RCP are in general pretty decent looking and they enable all the native controls and functionalities of the host platform.
Why? What value is looking good? There's value in a well designed responsive UX, but how it looks is completely meaningless to me because it doesn't help me get shit done.