As with the previous comments, if you would like the chat to be quiet, use the default Minecraft settings available to you. However, there have been times for myself where I would like to still chat in other chats but not see nation chat.
There have been times where my nation chat has just been exploded with a crap ton of people talking. It is a bit of a nuisance to have to leave the nation and be invited back later. Often times these types of chats come out of no where, and makes things a bit difficult if I'm trying to just talk in global chat or even trying to read some info within the chat.