When I (CRM) ask if they mind if I have a play, it's again, a load of excuses, such as too tired, or weather's not perfect... or they'll report me!
If you are PIC and commander why do you have to ask permission from F/O to hand fly an approach? That is 'supposed CRM' gone mad. Announce you are disconnecting and just get on with it.
Just curious about the operator, but you can keep it anonymous. I don;t know all B737/757 operators, but those that come to mind I thought encouraged such antics.