And how do you know that they did change rather than what St. Ignatius wrote being a true reflection of the what the Church believed from the beginning?
During the period the Apostles lived decisions were made as a group after praying for guidance.
If you look at Acts you will see that the dispute over circumcism was not settle by the congregation at Antioch but rather that they sent a delegation to see the apostle and priests in Jerusalem for a decision.
1 And some coming down from Judea, taught the brethren: That except you be circumcised after the manner of Moses, you cannot be saved.Thus we clearly see that it was assembled hierarchy, and not the general congregation, that settled the matter.
2 And when Paul and Barnabas had no small contest with them, they determined that Paul and Barnabas, and certain others of the other side, should go up to the apostles and priests to Jerusalem about this question.4 And when they were come to Jerusalem, they were received by the church, and by the apostles and priests, declaring how great things God had done with them.
6 And the apostles and priests assembled to consider the matter.
I suppose it is a typical human failing to want to "control" everything including outcomes.
It is, which is why some would seek to deny the proper authority granted by God to apostle and the bishops as their successors and seek gain power for themselves.