Sum of Story Estimates doesn't roll up to Epic????

[Vijay Sv]

I wonder why Jira doesn't provide or come up a solution to roll-up Estimates from granular tasks/Story/Sub-tasks to top-level Features or Initiavitive or Themes. I understand currently sum of estimates are rolling up to Story level. But why can't we have a basic feature of rolling from Story to Epic or any higher level we customize?? Why Atlassian recommends using Portfolio management plugins? 

Are they any such Features in pipe-line that Atlassian is thinking off? I feel these basic features should be considered when the whole world is running behind Agile practices.