Truth be told, the reason why grim reapers were mandated to stay in the mortal realm and got to live amongst with the mundanes were not just because to make their job of fetching deceased souls within their area of responsibility a lot easier.
The main reason was that for them to teach a lesson.
Only when a grim reaper learned how to value life and started feeling sorry for not having a life of their own would they be finally relieved in their service.
It was for that reason that grim reapers were meant to feel hunger and eat like a typical human. The same as to why they were also required to rent a house and pay for daily living expenditures and lived basically just like any other mundane did.
It was for them to eventually wish to have a life of their own again and learned how to value the life that they once wasted by committing suicide.
