It's very simple. It behaves like users would expect something like Word to behave.
Editors like Vim have a learning curve because they introduce the concept of modal editing which takes some getting used to.
I can't even properly explain why I like Vim. I guess it's the same way, by habit. When in a non-modal editor I'm just very clumsy. Trying to type commands but inserting text instead by mistake and so on.