For all those who want to have a better understanding of the topic, there is an article on Aish.com that I would recommend reading. You can find it by googling. It’s called “Is the Midrash literal?” by Rav Yitzchak Adlerstein.
He explains the topic pretty well, but it is important to remember that he is writing for a particular audience, so there were certain important points that were left out, namely:
1. That the issue is not that Midrashim CAN’T be literal; the question is whether or not they are, and I think it is possible that there can be a hashkafic problem with not being able to believe that they CAN be literal.
2. My understanding is that there are Midrashim that are meant literally.
I would also recommend reading the article on Vashti’s tail by Rebbetzin Heller on Aish.com