What was one of the most helpful reforms that took place during the Reformation?

Joel Beeke explains in this video that one of the most helpful reforms was Sola Scriptura - the understanding that Scripture alone is sufficient. Acknowledging that Scripture alone was sufficient elevated Scripture to its most proper place. The Reformers understood that Scripture is our authority, that it is sufficient, and that it is not necessary to be an individual in the Roman Catholic Church to understand or read it.

Scripture is clear and authoritative in itself - not because the church says it is. God’s Word teaches us and it guides us. Ultimately, Scripture is the foundation of every part of our lives.

2 Peter 1:20-21 (NKJV) – “[N]o prophecy of Scripture is of any private interpretation, for prophecy never came by the will of man, but holy men of God spoke as they were moved by the Holy Spirit.” 

Concerning the question of what particular reforms are most helpful for the church and for us today, I think the first of course must be the elevation of scripture to its proper place. The idea that scripture is our authority base, that scripture is the center of our thinking, that scripture is sufficient, and the perspicuity of scripture, which means the clarity of scripture, that the average layman can understand the basics of scripture without needing the pulp for every little interpretation. That, yes, the Reformers can help you understand scripture better, but scripture is clear in itself. Scripture is authoritative in itself. Not because the church says it's authoritative the church only recognizes its authoritative now that Is critical for today the church is our mother the reformers said so it helps us Nurtures us it guides us in biblical truth, but it's the Scripture, sola scriptura.

That is the foundation of our lives. You