Ever since Minecraft, there has been an explosion in this voxel based and block based sandbox builders. Some of the games are, unfortunately copies of Minecraft. After the release of Minecraft, people started realizing that, from a game play perspective, that having no goals is boring. So that alot of game devs started learning from that and attracting that niche of the market (including me), by creating sandbox games that has set objectives that also allows some freedom without being too boring.
There are many of these types of games, yes it might be out of hand, but the good ones are really good and successful. And the bad ones we see just sink down and no-one really notices.