Damian Lillard is the best rookie in the 2012-13 class and deserved to be recognized with an All-Star selection. 

There were questions about how quickly Lillard would adapt to the pace and physicality of the NBA, as there are with all rookies, but Lillard's defied the odds. Despite being just 22 years old, he's put up excellent season averages of 18 PPG and six APG.

His adept vision on the court and decision-making distinguish him from the majority of point guards across the league. Lillard understands passing lanes and has rapidly learned how he can help his teammates thrive, whether its J.J. Hickson or Nicolas Batum, both of whom have had their season averages increase this season (coincidence? I think not).
Lillard is on his way to becoming a dominant player and was robbed of an All-Star selection.