I share the same sentiment about how All-star starters are selected, but All-star festivities are usually dedicated for fans so we really can't argue about who the majority want to see. The main problem is that the promotion of players is unequal. I mean despite the struggles of the Lakers and Celtics, Kobe, KG and the rest of the gang are more exposed to the media (highlights, articles, promotional videos, etc.).
The best way for this is to limit and filter the selection of players then from the crop the fans will choose who they want to see, as MAStamper suggested. Or have the fans' votes have 1/3 weight and the other weights will come from coaches and/or players themselves.