It's NEVER appropriate for a manager to be dictatorial. It IS appropriate for them to dictate proceedings at times, however, such as when there's an emergency or a major crisis and things have to be dealt with on an 'act now, discuss later' basis.
The manager who adopts a general air of dictatorship with his or her staff will get nothing done. It's the one who has worked to gain their trust and respect who can rely on them to 'do as they're told' without question in a crisis.