because it's a false dichotomy and it shouldn't be how we approach the law. the law is like a forest but this dichotomy approach is like drawing a line in the dirt around 10 trees and saying look at these 10 I'll call them the moral trees and these are the ones we should follow. The 10 are part of the forest and drawing a line around them doesn't change that nor does calling them moral make them more moral than other laws or make the other laws less moral. When isolate the 10 we make them incomplete and thus their message incomplete because they function with in system not outside that system. the law points to Christ, and the more law we include in this the better it points to Christ. breaking one aspect of the law still breaks the entire law, the 10 are not special in this regard, and we are still guilty if we break something outside the 10 as we are inside the 10.
The law exposes our guilt and this is it's function but it does not nor it cannot fix our guilt. because we are guilty it creates a demand for something greater than the law to fix us and this is Christ. The fall of man has a similar focus. Ths purpose of the fall shows we are in a fallen state that we cannot get out of or fix ourselves this need something or someone to redeem us which again points to Christ. Summed up, the fall and the law accomplish the same as Rom 3:23 summed up "all have sinned and fall short of the glory of God" without events like the fall or without the law telling us we guilty we may come to the concluson we do not need a redeemer... some sort of Pelagianism heresy or that we are gods outselves.
equality with god is part of the motivation of the original sin. The snake's reply is "For God knows that when you eat from it your eyes will be opened, and you will be like God". upon eating the fruit it infact did the opposite and separated us from God. Abstractly though we don't need to eat a fruit to be separated from God. We are separated with God because we are not God and despite being made in his image we are not limitless in all ways. Adam needs a redeemer before the fall as much as he did after the fall simply because Adam is not God. if Adam didn't need a redeemer before the fall then this is tantamount to calling Adam a god himself. The point of the fall shows us we are not God and we are in a state in need of redemption in order to approach God but we will never be God himself. The creation account shows us first there was darkness that light is spoken into, and this was well before the fall of man. A priestine sheet of paper burns up just as quick as a tarnished one if thrown into the fire so it really doesn't matter how "perfect" we are, we still need a redeemer so that we may approach God. This is the role of things like the fall and the law. they both point to Christ by showing us our need for a redeemer. Well before the law and well before the fall there was darkness in need of light which is the core of the gospel message. We don't need the fall or the law to know light needs to be spoken into darkness and since darkness seemingly preexits the creation account Christ was always needed and there was never a time when Christ was not needed.
We're not children anymore and these aren't sunday school stories. We need to approach the bible knowing it has revealed to us a truth that wasn't known in by Moses or Adam. All these accounts have a common goal and meaning, they are not arbitary and they have immense depth and purpose. We need to approach these accounts like we beleive this.