All issues in the backlog have the same status as the first column on the board. This means that when looking at an issue via the issue view (say, via a search) it is impossible to tell if a "to do" issue is in the backlog or on the board. It's also impossible to move it onto the board from the issue view, or vice versa.
This leads to a cumbersome workflow when moving items back and forth between the board and the backlog. You have to find the issue via the board or backlog view and make the change there.
You should be able to see and change whether an issue is on the board or the backlog when viewing the issue directly.