The point is to increase your skills and improve your gear, so you can make more cool stuff and kill more baddies. The other point is working together to accomplish goals. The
other other point is exploring the world, because it's beautiful. And on Wild server, another point is furthering the war effort.
For instance, right now the group is working on rebuilding an amazing settlement (originally made by SA goons some time back). Personally I'm working on healing, gathering, farming, and metalsmithing skills, while others are working on whatever they like and needs doing. Some are into cooking, some weaponsmithing and fighting, some mining and carpentry. Then there's personal challenges you can set for yourself, like Sappho who is determined to be the first to the peak of the tallest mountain in the land. Eventually we may move on and build our own site, maybe at the top of that mountain! Of course you may choose to go it alone, too, which makes it more challenging to complete big projects, but potentially more satisfying if you manage it.
Basically it's very fun and rewarding to make and do things that help you and the group. Every "quest" is dictated by the actual needs of the group, or is something that helps you reach your goals, so everything you do is meaningful. Instead of being told "Go bring me 10 plump helmets" by some stranger, you *want* to go find 10 plump helmets so you and your friends can use them. It's fun (and free)!