Nope, I only needed them for extra design space back then, as did everybody else. Now the houses will just take up space on my island so I definitely won't be creating any alt characters.
I have ideas for other buildings in town aside from
the traditional AC ones so if I create an additional character it’ll be so I can use their home for that purpose! I really want to create a cafe owner character who owns a bakery/cafe on one of the upper levels of town, as well as possibly a character who runs an onsen/bathhouse. I have to do a lot of reorganising and terraforming before I can even think about creating them yet tho
I don't plan on having any alternate characters in this game, as my current plans for my island don't need any of them. Plus, there's already two characters in town because of my brother (who's barely played it, compared to me) and I. If it ever did come to it though, I'd probably just make them for storage (which I still have plenty of).
The only time I made a full set of characters in the AC series was in the Gamecube one. It wasn't because of storage, I just wanted to have cute/nicely decorated homes around mine.