I agree with this, or maybe some kind of item that you can craft cheaply similar to a nail where if you attach it to a prop then the reset will ignore it or a radius around it...?
it's probably difficult to specifically filter out what was placed intentionally by the player vs what was not intentionally modified... but it would definitely be nice to be able to reset events without also resetting items. maybe this would allow for duplication of event items, so probably you would have to be careful...