That's an excellent suggest! The one thing I did not explain, is that one control can be used for more than one item.
Maybe the best way to explain this, is by drawing an image. On the left side of our settings dialog, we have a tree control with a list of items. When a user selects an items, the controls on the right side populate with the items details. Such as its name.
The user can go in and change all the items names, and then save at the end.
So the tag field wouldn't work in this instance, since the value for the control will change when the user selects different items.

I have a feeling this way to confusing to explain.