That's a simple description, not a simple explanation, and yes there's a difference. An explanation has the additional burden of being easy to understand, which your "simple" explanation is not unless you already have a background in category theory or other relevant experience. What's an endofunctor? What's a "natural" transformation? Is it something more specific than "just a transformation"? What in tarnation is a Kliesli construction? I'm sure you can give good answers to all these questions, but at that point your explanation is neither simple nor easy.

I'm not saying they're bad, I'm saying they're hard, and your pitch needs to be that they're worth the effort, not "come on, they're not that hard". Until I saw your reply to your other reply, I truly thought this was a joke. In fact, the "monoid in the category of endofunctors" "explanation" is a classic joke about haskellites.

edit: typo