Sometimes, I hear myself (and others) provide a "simple" explanation of a topic. I think describing something as "simple" subtly excludes those who do not find the topic simple. At the very least, this includes everyone who is new to the topic. This can be counter-productive, because the reason for providing "simple" explanations to a topic is usually to introduce the topic to newcomers!
Instead, I think that introducing a topic with a "simplistic" explanation is not only more accurate, it is a friendlier way of signaling that the explanation is for beginners. "Simple" implies that the topic should be simple to the audience. "Simplistic" implies that the topic is complex.
I prefer the latter.