it's an interesting discussion, domination psychological and physical

as it has already been pointed out, in consensual BDSM there can't really be any physical submission without the mental submission first

before you can snap on the cuffs, you first need the willingness to let you put on those cuffs
- at least I suppose that most people prefer not to have to run after and try to catch and overpower their mate every single time they want to do some bondage -

anyway in practical terms for me it depends on the mood
sometimes it's great to watch the pull against the rope
sometimes it's great to just say 'Stay like this!!'