Too many issues are reported without a link to a demo/test case, and many of those issues (eventually) end up being closed because the reporting party refuses to create a test case, or while creating the test case realizes there is no bug involved.

In order to increase the "link to a test case" rate in new bug reports, I suggest adding an input element for that purpose on http://bugs.jquery.com/newticket, in between Summary and Description (and update the template that renders an issue to render the new field/link). If you do that, then you can also add additional "validation" (client or server side) to detect when no link is provided and warn and encourage the user to create a test case and provide the link.