I feel like that could make some forms of centralization pop up. If you have all these currency notes, who's making them? Someone's gotta manufacture and make those notes and coins. Also, I think the strong benefits of using bitcoin come from the fact that you have a lot of flexibility and precision in how much money you want to send to someone. If we make some kind of notes for BTC, you lose out on that pretty nice benefit. Genuinely, we as a society are likely going to be moving away from currencies that are physical and move towards the electronics based ones. They're just a lot more fitting when it comes to the future and potential uses for crypto.