Defending the possibility of innovation in doctrine is just another way of asserting sola Scriptura. It’s a way of saying that the church is accountable to the Word of God, and that the Scriptures have yet more to teach us as the church encounters new challenges. Protestantism is at stake.
But not just Protestantism. Asserting the possibility of innovation is also, as Barth understood, a way of insisting that Christ is the Lord of the church, and that the church is not her own lord.
It’s also a way of asserting the freedom of the Spirit.
So: A lot is at stake in the way we construe the relationship between tradition and innovation.