Because if we want it to happen quickly then it would need to be an all-hands-on-deck situation. For a substantial overhaul to in-game systems it would be of great benefit to have devs from all areas of the game working together to combine their knowledge and ideas. It can't all just be back end coders and the like, they'd need real knowledge of how the game functions on the player side as well as how it works in development as well.