I don't think there's anything purposefully misleading about the intentions of St. Patrick's Day. It was meant to celebrate St. Patrick's works in Ireland so the church lifts it's Lenten restrictions on the consumption of alcohol (and the other fun things like sugar) on that day to allow adherents to celebrate.
I think the part that can get a little twisted is that it's also seen as celebrating Irish culture and then the stereotype of alcoholism that's used by the English to continue oppressing them gets reinforced. So that's sad because I don't think most people ever think about how the conquered feel.