Why does everyone talk about the need to vote when it's the super delegates that decide who wins the election?

If either candidate had secured enough delegates without them, then the supers would not be in the position to be the ulitmate deciders. Unfortunately, that did not happen. However, most of them are elected officials, and are unlikely to go against the will of the people as expressed in the primaries and caucuses. They will do what they need to do to protect their own skins, and that is to support what the people said.