This would be useful because we have a support team working in Salesforce to work through customer cases and the development team working in JIRA while solving the root cause. We have a sufficiently complex system such that it's not always obvious to the support team (or even a developer) if the root cause of two cases are the same. Once the development team has investigated the issue in depth, Salesforce cases may need to be split into multiple JIRAs or merged from two different JIRAs into a single JIRA. The dev team should be able to correct the associations directly within the tool they're using, which is JIRA.
A bonus feature would be to automatically move all cases from one JIRA to another when closing the first JIRA as a duplicate, but that is a nice to have next step.
Thank you for raising/upvoting and commenting on this idea. Our team has analyzed this idea and since this idea is not in align with our roadmap we will proceed and mark it as "Will not implement".