I love these threads where Michael is explaining his rational for features, specifically:

"Things like a permanent extra button means that some beginning user who just wants to do simple things and doesn't need to do any filtering will pay some price in UI complexity for something that they don't use. That's the kind of thing I'm trying hard to avoid."

Implied in this is an often overlooked psychology principle, hierarchy of knowledge and its unconscious effect on emotions, which is required for efficient teaching/learning.
Its at once disheartening and exciting to see that while my University professors are forgetting it, Michael is actively employing it in the indirectly related field of UI design!

I believe that its such things, considered small by modern standards of judgment, that are the reason why many people are grappled by MOI, at first emotionally and then intellectually.