I think the "do this or I'm leaving" argument usually comes off poorly unless it's about something truly intolerable about the workplace. As a manager, whenever I hear that, the only thing I can think of is who I need to realign to temporarily fill in for this person when I tell them "okay, go ahead".
Once you give in to that kind of ultimatum, you set yourself up in a negotiating position where all any of your employees have to say is "...or I'm leaving" and you've basically agreed to give away the farm for sometime truly inconsequential stuff (employees talk between each other and a successful and simple tactic like this will spread like wildfire).
Once you give in to that kind of ultimatum, you set yourself up in a negotiating position where all any of your employees have to say is "...or I'm leaving" and you've basically agreed to give away the farm for sometime truly inconsequential stuff (employees talk between each other and a successful and simple tactic like this will spread like wildfire).