Why should a publication present results in a way that significantly differs from the discovery of said results?
I think this comes down to the subtle but important difference between communication and education. The target audience of a research paper is experts in the field, not students. Most readers want to know what your theorem says, why it's important and relevant, intuition about why it "should" be true and why the proof works, and (sometimes) the details of the proof. Few people are reading in order to learn how to prove theorems, which is what your suggested presentation would serve.

Having said that, it's possible to take the "uneducational" approach too far and actively cover one's tracks, so that the paper is hard to understand but looks impressive. By all means, if an informal discussion of the special case "X" will help give intuition about the main theorem, include such in your introduction.