One of my favourite things about Harvest Moon and like games is making friends as a game mechanic, and one of the most appealing things about MMOs to me is the social aspect, but to be honest I am really shy and don't always know how to start talking to fellow players in a game.
I think it'd be really neat, especially because dating/relationships are a part of the game anyway, to have a lot of game mechanics that encourage people to meet and actually talk to each other. I'm sure the developers already have stuff like this in mind, but I just thought I'd like to throw stuff out there.
There could be event challenges like pub quizzes, scavenger hunts, or relay races, where players are sorted into teams based on some common interest or personality trait (like if you want to participate you're asked "Would you rather have a pet sphynx or griffon?" or "Choose these colors in order from least favourite to most" and then are grouped into teams based on having the same/similar responses).
There could also be individual quests that encourage you to talk to other people or other people to talk to you.
There could be themed chats in certain areas on certain days, like essentially fan clubs. So there could be an announcement "Do you like Harry Potter? Well there's a wizard themed chat happening at this location on this day with prizes/games!"
White elephant gift exchanges could be fun, or secret santas, or items that reward the people around you but not yourself (so are purely for spreading the party!).
In game pen pals that you can be matched with and play together and write to each other. In game voluntary mentors/mentees, where mentors are matched with new kids to help them out.
Pretty much any "getting to know you" game you can imagine playing at a party would be fun to be able to play in game with people you don't know.
There could be ways for players to announce to those around them that they're looking for people to play with, and maybe even list an interest or trait they are looking for. Maybe an icon showing they're open to play together.
The big thing I want is a way that the game makes it natural and fun, and even maybe rewarding in-game, to talk to each other without some kind of Gaia-esque spam or popularity contesting resulting. And with the game still being playable if you're feeling antisocial. But making friends with NPCs is a big part of the mechanics of Harvest Moon, and it'd be fun to have that with each other as well somehow. Some way to make it fun to be nice to each other, and make it hard to be mean, and easy to start a conversation with a stranger if you're looking for someone to chat with while you play.

