According to Andrew Greeley, one of the reasons Catholics stay with their religion in spite of every mistake the church can make is that the Catholic religion has great stories. Story and metaphor is how we make sense of our lives. This doesn't mean literally. My husband is an unreconstructed pagan, imprinted early by Hawaiian mythology. He says there are many different versions of the creation of the world, and they are all true. That is "true" in the sense of "meaningful." Trying to make literal, logical, Western sense out of Hawaiian myths will get you laughed at.
So it isn't a big deal to me whether St. Patrick was real, whether all the legends associated with him really happened, or whether he cast all the snakes out of Ireland. (Personally, I think he now wishes he had left the reptiles and cast out the politicians.) The myths, legends, songs, stories, games and traditions that have grown up around him are fun, and help encourage the sense of wonder.
The only thing I personally have against him is that he had a tendency to baptize fairy folk, and then they died. Which is a metaphor for the passing of the old ways as Christianity advanced.