The 2008 primaries had a huge turnout, particularly among young voters. I guess that was because people were excited to end the Bush era, the nomination was contested for a while, and Obama was drawing people to the polls that didn't usually vote (young people and minorities).
Election 2008: Primary Turnout Story: Presidential Races Miss Record High According to American University's Curtis Gans
Maybe people would have been just as excited about Clinton if it was just a coronation for her, being the first women nominee and president would have been a huge deal too. But I just don't buy her inspiring people and getting them to the polls the way Obama did.