Yes please a useful sidebar would be amazing (always visible would be the dream). I don't want to have to go to the bottom every time to make simple changes. However I definitely did use the edit everything at the same time page very often, so the bottom area is actually lacking in a couple of things (edit title, attach files).
All the information I want to see
Edit Ticket button to take me to the "Edit everything at the same time" section at the bottom.
Votes or "Subscribe" button for users to follow an issue they care about with a count of people who have (This along with comment count was useful for seeing how important an issue was to users)
Attached is my mock-up, although I'd probably have it within the normal width of the page.
Put most general information into the sidebar and left the main area for just issue discussion. (Personally I'm not a fan of the history being in-line between the comments as it feels cluttered, but I doubt that'd change at this point).
Moved the Attach button at the bottom under the comment box (ideally you'd comment when attaching something)
Got rid of the Unassign button (the Assigned to dropdown should do that)
Moved the Unfollow button next to a new text about follows
Added an "Edit Issue" button which would take you to the comment box at the bottom so you could do all your edits at once without scrolling.
Moved entire page content up
Added Title edit box to the editing section at the bottom