Winning Iowa, or at least winning expectations, correlates with additional fundraising and additional support leading into the following states: NH, SC, FL, NV. A winner is able to build up momentum into those states and have the chance to continue a successful campaign (Obama for America 2006-2008). And to be honest, Iowa and New Hampshire both are special. I've been to both states countless times and the people are fervent in understanding today's issues and the candidates' stances on those issues, more so than any other state in the country. But you are partially correct with your final assessment, winning Iowa does not guarantee a successful campaign run.