There are some dashboards where we don't want people messing with the filters. Or where filters aren't needed to be changed, and we want the maximum "real estate" available for the body of the dashboard.
I know you can hide the left- and right-hand panes with script, but this really should be an option exposed in the dashboard designer UI, as a setting for that dashboard.
Example:
Filter Pane: Show [default]; Collapsed [but user can expand]; Hidden [user can't expand it]