Despite the plot of the game supposedly encouraging heroes, a section of the game's storyline involves the heroic Demolicious' defeat at the hands of the villain Luigi daVinci. This happened because of a glitch that was exploited by dishonest players during the decisive battle in the early stages of the game. (A player at the time of this review can no longer change the results of the battle.)
Due to this, many players flocked to the villains' side, and a vicious cycle began. While the game obviously doesn't make wickedness an exemplary path, many players on the villains' side may encourage new players to join them as the playerbase of villains is much more powerful than that of the heroes.
Parents can take the opportunity given by the events of the game to discuss peer pressure with their children, and how one can resist following the crowd if this is not what they wish to do. Otherwise, parents have to tell kids that villainy is not cool in the real world, despite what a virtual world may imply.