I have a question. Why do so many feel they must vigilantly defend their decision to homeschool?

So much of the dialogue I read regarding homeschooling seems to be centered around defending/justifying the decision. I admit to having done this, however, at some point, I realized that it was no longer important for me to do this. We homeschool our child and have enjoyed the benefits and frustrations that come with it. I am not sending this to you as some sort of troll. I have found your blog entries to be honest and thoughtful and wanted to pose this question to you.