I mean, from a design standpoint, he has clear purpose. AC games don’t have an autosave function, and it seems to me that it’d be hard to have one that was lightweight and didn’t add unwanted time to loading screens when entering or exiting buildings, making purchases, etc. Since there is no autosave, players have to do it manually. Sometimes people forget, or they abuse resets for random drops, like items from Pascal. Resetti was put in the game as a reminder to save all your hard work, and as a deterrent for people who would try to get specific items from random drops and events. He’s a form of in-game “parenting” in a way, since you are technically playing the role of a child starting life on their own.
And his character, in its entirety, is rather genius. My first encounter with Resetti was rather interesting for me, since I didn’t even know about him. I was shocked that the game knew I didn’t save, and what’s more, I was shocked that there was a character in the game who would reprimand me for not saving. Every time I had to cross paths with him, I was not once upset by him in the way that some apparently are. I mean, I’m hearing things of some kids almost being scarred by encounters with him. That kind of thing makes no sense to me at all. Frustration with having to sit through his speeches if you hit the wrong entry? It’s no worse than the giant owl in Zelda OoT.
If you have to run into Resetti and you come to hate him, you have only yourself to blame, and you should know he’s coming.