Sorry, I mis inserted my own message in his quote first. I fixed it.
Well, yes, the shortness of the Luke could be a factor, but logically, if Luke did indeed take the armor off of a Stormtrooper, then they can use the same Stormtrooper armor with a ANH Luke head. This is because if he did take the armor off a Stormtrooper, it SHOULD be too be for him. Because of this, the Stormtrooper Luke would only need a new removable Stormtrooper helmet to make. All of the other parts have been made already. So then they should have just given the Stormtrooper a Han head with a removable helmet. It would have been relatively inexpensive to do, and have given people an additional reason to buy a Stormtrooper figure.