Hi there Dan. Good question. And how did the fellowship meal become a formal sacrament? And how did baptism go from being immediate to "first, a long course of study"?
Brother, I don't know but I suspect that each time frame had "heretics" which early Christians thought needed a special creed to address. Just as most of the New Testament letters were occasional - not merely sent out as doctrines alone.
We need to look into this further. There are several passages in the Bible which scholars believe were short creeds. Just a few sentences long, though.