Those "lego minifig" models are the old, completely outdated and unpopular version of Blockland. Playing it is just absolutely a waste of time considering the game doesn't start becoming laggy around ~800-900 bricks if I'm remembering correctly. Oh, and its full of kids who don't want to pay money for our shiny retail game.
Once those armless, legless rayman like blockheads were released in what we have today, aka "Retail" Blockland (now just referred to as Blockland), the ID system was put into use to prevent identity fraud.