It would be nice to have JQuery UI tied into outsystems for use of themes and pre-built ui components.

https://jqueryui.com/demos/

I know some of these components are built into RichWidgets, but it could be more helpful to use these components since there is a broader community building these components.

jQuery is now packaged with the OutSystems Platform, allowing you to easily reuse jQuery plugins in your application. Just use the $. notation.