Every presidential election is historic.
Agreed, but they usually do not “change” the course of history, at least not they way this action would.
Many voters believed that the election of Hillary would lead further down the road that Obama was taking us, and wanted to change that possible trajectory.
An Electoral College vote for Hillary would “prove” to the vast majority of those voters that the government was indelibly corrupt, and that the need to obey a government of that type was no longer applicable.