I'm from a part of the world where people regularly die by going for a walk unprepared (google 'tourist dies in outback' for a repeated history of such).

Having said that i cycled a fair way across Europe in my youth with nothing but a light bag, water bottle and wallet in my pocket.

So basically it depends. Yes you can get away with it in certain parts of the world but i would never argue for unpreparedness since it's way too common for people to die from lacking the basics of preparation.