It isn't necessary but if it could be implemented it may as well be useful. Use your imaginative understanding and put yourself in a staff members perspective. Making it so regular members can't message staff cuts down on a lot of the message they would get, along with also insuring a lot of immaturity is taken out of the picture. Ranks tends to be more mature literally because of the fact that they know how to obtain a rank and the fact that they have it. No it isn't fair, but guess what, by that logic, us having Elite Survival isn't fair either.
This is, in my opinion, necessary for ranks only, because it can easily be abused if not. Immature uses of this command would just make staff hate it because all their chat becomes is immature normies, they are the majority on the sever, if you haven't noticed. There can be a section of the forums where regular members can apply for permission to use this rank too, if that pleases you.