For many of my clients with web based projects we'll use several control suites such as Telerik Kendo UI, DevExpress DevExtreme, jQuery UI, Bootstrap, or Infragistic controls. It would be stellar if we could import the control packages based on the provided JS and CSS in order to make use of those controls out of the box. An example of why this would be great is many of the controls in these suites might not be possible at all with XD... a progress bar, timer, data grid... but they're needed at times to display crucial UI elements.