I think that online games to have staying power they must have an aspect of baking bread in them. Koster in his many sessions at this year's GDC talked about how there were two kinds of attributes about an avatar, the tangible and the intangible. Tangible attributes are things that the server can keep track of, like strength, hit points, magical energy. Intangible elements are things like if the person behind the character is a good leader, if they are trustworthy, if they are good at tactical combat. Raph pointed out that if you can convert as many intangible attributes into tangible ones, you'll get the audience to stay in the game longer, because they won't want to lose the tangibles they've built up in a community.
Intangible elements travel along with the person, while tangible elements stay on the server.
Crafting, or it's code name baking bread, is a good way of making lots of intangible things tangible. But there is a certain pleasure in working as a simple craftsman. Fans of the Harvest Moon console game know the joys of being a simple farmer. There is the satisfaction in simply creating things, then there is the challenge and skill of building a profitable business, and then there is the achievements of making it to the top ranks of the crafter ladder, making items that are sought after and are a mark of distinction. But as a way of appealing to all of our human instincts, creation, and destruction, bread baking is no more strange to do in a virtual environment than sword fighting is.