Improve Jira issue type hierarchy

Currently, the Jira Software default hierarchy contains:

Epics - Once the higher-level priorities are settled it's necessary to break them down into large pieces of work, which consist of multiple stories.
Stories/Tasks - User stories capture functionality requirements.
Sub-task - Work components that makeup stories.
Although Advanced Roadmaps allows users to add hierarchy levels above the Epic level, the Epic/Feature/Product Backlog Item (Story)/Sub-task hierarchy relationship has been a standard long before portfolio management came into play.

Jira has taken the approach that an Epic is the highest work item and then all others are children of an epic. The concept of features is common in agile software development that Jira is missing. Having a product that has an epic categorization should have multiple features of which multiple PBIs (product backlog items) and sub-tasks can be many. A story is but one type of PBI.

We would like to be able to use Initiative/Epic/Feature/PBI (Story)/Sub-task as the standard hierarchy from which all data can be measured.