Pros of having a publicly available GP list:
-Players can easily search someone knowledgeable of the game for their questions.
Cons of having a publicly available GP list:
-Spam sent to GPs: Messages like "Hi", "What's up", "Can you host events" etc. These distract GPs from their more serious tasks. PM messages should be the last thing they check after reports, uploads and feedback.
-Creates the illusion that certain players are more powerful than others.
-Staff can easily be harassed. There's a notable history of players verbally assaulting staff members. Removing the list does not prevent so but dramatically it. Newer staff members have also been victims of hacking attempts. The transition from player to staff member should not be too over-encumbering and having them change the password of all their accounts, set up a proxy,etc is not an experience they should be forced to do.
-Hackers, sexual predators, etc can add the entire GP force to their friend list. They are much more prone to their misbehaviour when they know that no one is online to stop them.
And this paragraph is for those who want a staff board so they know who to criticize for their work.
A GP member's performance cannot be judged by a player. Their warn/ban history is not disclosed to the public. Moreover they are 99.9% stealthed. Figuring out who banned who is purely speculative and having a board narrow it down to 20+ names won't help you.