Sola Scripture was a historical reaction to the oppression of the church using scripture and tradition tyrannically. Today, confessional protestants tend to take seriously creeds that are considered historically viable and flow from the voice of scripture.
Yes, it was an historical reaction, one that is not rooted in the foundation of the Church nor given by the Apostles. "confessional" Protestants today do have a bit of a love affair with the earlier Councils...at least the parts which they can agree with. Much of the detail within the councils is excluded, together with the later councils in totality. Why? What changed? The councils no longer fit the need of those denominations to prove themselves as truly "historical."
As Luther said, What is tradition? People in constant disagreement over interpretation and acton. To me, no Christian sect has an interpretation of history (or holy history) that seems truly consistent.
Luther, quite frankly, was wrong. While there is certainly place for theologumenia, Orthodoxy is what has been believed by all, over all time everywhere. When one deviates from that, they are heretical. This is what the councils were for, to correct and elaborate on those parts of Tradition which were being distorted. And yet...Protestants don't except all of those early clarification, even though the very last one was established and accepted centuries before the Reformation. Interesting.
Lutheranism, more than many protestant denominations, attempt to take seriously the creeds but because of the experience with Rome, their was a search for a higher authority... thus, scripture was it. At the time, it was the only answer.
Yes, Luther (and therefore Lutheranism, at least the small remaining number of traditional Lutherans) attempts to maintain more of a connection to the early church than others. Maybe, at the time, that was the only answer. What about now? It is a mutable doctrine? That doesn't sound like the unchanging truth of the Gospel.
The point remains, he still interpreted Scripture on his own, apart from any established Tradition, and elevated Scripture to a place which it never belonged.