Use the tell system to tell private things. Honestly, there's zero need for what you're asking for. If you're talking, you're probably not really doing anything else in the game. Why not meet up someplace where no one else goes and use local? As I've said, I highly doubt anyone is intentionally talking to more than one person at the same time. There are people who enter conversations between two people. However, it's rarely found in human nature that someone intentionally initiates a conversation with multiple people. Here at university, 20k people... I've never seen it done. A conversation doesn't necessarily mean everyone who's involved, but rather means who the statement is directed towards. When you say something, 9/10 times it will be directed towards one person only, I can pretty much guarantee that. Therefore, having a party chat would be useless, and more work than using the tell system. Why? People need to log in/out so they can see without any chunk errors. I need to do so roughly 3-5 times in a half hour period. That is due to the connection between the server and I. Sure, I get 4 bars connected to the server. However, when more and more people log on, the connection get's shared with everyone, meaning I get less and less, regardless of my connection speed. Therefore, you'd have to add someone to the party almost every 10 minutes. As well, when the party leader leaves for a chunk error or has to get off the game, the party chat no longer exists. There is way too much work, that once implemented people would whine and complain about how difficult it is to use, and then only a few people would ever use it.
Due to the above, this doesn't cater to the good of the server, in my opinion. From my understanding on previous threads about the same thing, this won't be happening either. Mod/admin, feel free to correct me about that.
In no way am I trying to attack you or ruin any reputation you may/may not have. I'm merely speaking theoretical argumentation combined with past experiences on this same topic, in addition to logic.