This is an awesome thread! Kudos!
Medicine: I think the biggest thing I noticed was that it teaches people to visit their friends when they are sick! It shows the importance of bringing your friend company & medicine when they can't get out of the house. I think that's very sweet & essential to creating a community.
Recycling: the Re-Tail shop is a really inspiring idea & a great idea for towns to do this in real life.
Various ways to be a good friend: I like how the game demonstrates how you can't be a good friend to someone by simply chatting to them or posting on their facebook. In AC you have to send them letters, help them out, find them nice & thoughtful gifts, attend their birthday, celebrate holidays together & give them medicine when they are sick.
You can also work on projects together like gathering signatures for them, or customizing an item---so it shows a real friend puts in a lot of love & effort.
Making your own goals in life: The people who complain the game is boring or don't get what it is about are missing this point.
Organizing & planning Turnip trading, visiting others, planning a town & theme...all use this skill.
Creativity: When you start making a theme town you have to get really creative with custom items, pro designs & PWP in order to make a really good theme town.
Quality over Quantity: You can only have 10 villagers in your town, so you have to work out who you you really care about & want around. It teaches you to tell the difference between close friends, and just friends. You also see who helps you out when bee stings your face (bad things in life) and who do you really want to spend your time with.
Giving people a chance: It often takes a while to move people out of town. Sometimes this is highly frustrating, over times it is a fantastic life lesson. I'm so glad the game forced me to befriend Wart Jr & Colton because they turned out really cool & sweet in the end.
I am not happy the game forced me to keep Chow, as he just became ruder over time. But I like how it makes you get to know someone before judging them too quickly. The same can happen when good looking dreamies actually turn out to be boring & bland after you really get to know them.
Grumpy people can have a heart of gold:-this one speaks for itself, i.e. my lovely Lobo.
It's a beautiful game, and that's just scratching the surface of the good things it demonstrates.