LOL ah Minecraft, I hear on that one
I know what you mean, I think the idea is to create a virtual life of sorts. Much like the Metal Gear, Elder Scrolls, Halo and Splinter Cell ETC series have done. Players get to move through different phases of the player character's life and evolve with them. While at the same time allowing room for people new to the experience to come in and not be left out in the cold as to the overall story of the characters they're playing. Personally, I really like this aspect of games that do this, but I also see the advantages of the one and done approach for racing & sports games or a lot of the first person shooter games. Like Call of Duty, the wars keep happening, but you never play as the same character or era. There's also the one trick pony aspect. A lot of developers do one thing, but they do very well. Like Halo for example, but it keeps the cash flowing, and this fuels R&D for the next gen tech.