At idea stage you capture information about the idea in multiple fields, when you promote this to a feature if this information was merged into one 'Body' field, then I would save time not having to copy and paste those fields into one field.
Having all the data in one 'Body' field would allows you to send it to one field in JIRA.
Thank you for your idea. As noted it is possible to map ideas custom fields to populate feature custom fields on promotion. One suggestion to streamline this scenario would be to leverage the description in the custom note field to give users guidance as to what information to add in the field. This will show up on the ideas form which may allow you to consolidate the notes fields in your form to a single field.
Given the option above and current priorities, we are unlikely to implement this idea at this time. We hope you can understand.