Thank you for your continued interest in this feature suggestion. At Atlassian, we draw customer feedback from many channels and jira.atlassian.com is an invaluable part of the process. Your input is crucial in driving the most value to all our customers in Jira .
The power of Jira allows issues to be more than simple tasks with a description and summary. Custom fields allow issues to hold distinct values, often with many restrictions and conditions that exist both inside the Jira application and externally via our Atlassian Connect framework. Considering custom fields introduces many complex use cases that must be considered before commencing work on this kind of feature.
Merging issues would be a significant investment from the Jira team which would require it to be explicitly set on a roadmap. It is currently not on any Jira team’s roadmap. Any updates on this will be promptly reflected in this feature request.
Please remember that jira.atlassian.com is one of many inputs for the Jira roadmap. You can learn more about our process here.
I understand that some many not agree with our current decision, so please don't hesitate to contact me if you have any questions.
Kerrod (dot) Williams (at) atlassian (dot) com
Product Manager, Jira