Copyright was never intended as an alternative mechanism for contract enforcement. If that theory is allowed to stand, it would dramatically strengthen end-user license agreements and create enormous liability for those who break them.
That would eviscerate the first sale doctrine and create tremendous legal risks for firms and free software projects that reverse-engineered other firms' products for purposes of interoperability. MDY may not be the world's most sympathetic defendant, but there's a lot more at stake in this case than World of Warcraft bots.