You don't need to take them out of the pocket to scan them. I used them in the shops, for our room, for bars, getting on and off ship without taking it out of the lanyard.
You used only to need that, but several years ago, they added a Bahamian checkpoint before getting back on the ship, so you need ID now. Whether anyone checks it or not is another question. They didn't check our ID when getting back into the port to reboard our ship in Cozumel two weeks ago or the Bahamas a few months ago, just the keycard. But it may depend on who is doing the checking.