I contacted Jira support about adding the ability to add a direct way to drag and drop subtasks between parents, and they graciously added the above feature request for me.
If you're interested in this as a feature in Jira please have your teams vote this feature request up! (Hit the 'More' dropdown to vote)
welcome to the community, and thank you for raising this!
If you're looking for an immediate resolution and are open to solutions from the Atlassian Marketplace, you may want to have a look at the app that my team and I are working on, JXL for Jira.
JXL is a full-fledged spreadsheet/table view for your issues that allows viewing, inline-editing, sorting, and filtering by all your issue fields, much like you’d do in e.g. Excel or Google Sheets. It also comes with a range of advanced features - including support for (configurable) issue hierarchies, issue grouping by any issue field(s), sum-ups, or conditional formatting -and worksacrossany number of projects.
Plus, it allows moving sub-tasks between parents via drag and drop, like so:
This works for sub-tasks as well as any other hierarchy level, and also across issue groupings of any issue field(s).
