That's not really an answer, but ...
1) Personally, I think the Memoji are really pretty silly, and I don't want to make one because,
2) I don't want Apple to introduce some bug, or change some default behind my back, where the damn thing unexpectedly or even unbeknownst to me starts appearing in my communications.
I'm sure the kids love them but I'd rather have a device that doesn't require me to make one and nag me if I don't comply. I consider that a very reasonable stance.