Why are Americans interested in St Patrick?

I'm fascinated by the lengths Americans will go to in order to celebrate St Patrick's Day, so I thought I'd ask American author Cindy Thompson why she was is interested in St Patrick.

"Oh, my goodness! St. Patrick’s Day is huge in America. But for Americans the saint means green stuff: green beer, green carnations, shamrocks, cupcakes with green icing…and it’s also a time for celebrating Irish America, which is a good thing. However, my experience has been that Americans know little about the saint himself. The stories we hear is that he drove the snakes out of Ireland, that he brought Christianity to Ireland, and that he explained the Triune God by using the three-leafed shamrock as an example. None of these things, by the way, is supported by historical evidence. There is so much more to St. Patrick than that!

Most people know that there were no snakes in Ireland—there still aren’t. It’s generally accepted that the reference to snakes was symbolic, either as evil or as the old religion. However, none of St. Patrick’s writings refer to snakes. He did spread Christianity throughout Ireland, however what most people don’t know is that there were Christians in Ireland before St. Patrick came to convert it. What a lot of Americans don’t realize is that St. Patrick was not Irish. He was kidnapped and brought to the island as a slave, and was born somewhere in Wales or Scotland or northern England."