What's the logic behind AoE 1 DE campaign changes?

I think some scenarios from demos were just repeats of the scenarios available in full games, so Hittite campaign gets a new second mission. And better history notes are understandable.
But some other scenario reworks are just strange. I think about a third of the missions are randomly replaced for something that looks similar and have similar objectives, but new missions nonetheless.
Was it ever explained by the devs why they chose to replace some scenarios? (and not the others?)