If you want a vent and chose a brass leash plug then a brass vent is for you.
You do not need a vent if you have a bung or Air Vent Screw and every board needs a bung, but it will give you time carrying your board in the heat before you need to take the bung out, allowing you to walk back around to that point before you jump off the rocks back for another wave, or you hope out of the water take the bung out, walk out to the point put the bung back in and off you go, your decision whatever works for you and where you surf .