Why is Logic So Hard?

I'm teaching Symbolic Logic this semester, and my students are doing very well. But when people hear that I'm teaching Logic, they often comment how hard they found the study of logic and reasoning. I have noted that too: that often students do find this very hard. Once you "get it," the principles are very clear. But why is it so hard to "get it"?

Recently someone I was talking with was wondering why logical errors of reasoning are so common. "You can spot errors of reasoning, and once you do, they are perfectly clear and obvious. So, why do people make errors of reasoning at all?"

I found myself answering: "It's because of the asymmetry of the conditional. That confuses people who haven't actually studied it and thought about it. Unless you really study it, it's not obvious that 'if A then B' does not always also mean 'if B then A.'"

Was I right? Is that the heart of the problem? Is this what makes logic so difficult, and errors of reasoning so common?