The thing to remember about Lutheranism, and most Protestant beliefs, is that it all spawns from reactions to 16th century Catholicism. The "sola scriptura" piece of it, from my understanding, comes from the view that Catholicism in the 16th century wasn't doing enough to teach the common people what is actually in the Bible and was also teaching things that are contradictory to the Bible. In Luther's view, some practices of the Catholic Church at the time were in contradiction to what is explicitly stated in the Scriptures (at least according to his own understanding of them). In Orthodoxy, Holy Tradition is the source of all our theology and practices and the Scriptures are the keystone within Tradition - meaning we wouldn't have Tradition without Scriptures. With Lutheranism, however, Scriptures are the prime source of theology and practices; I remember a Lutheran I met years ago once summed it up as "we have traditions and maintain them as long as they don't contradict Scripture".
A huge part of the problem on the dawn of the Reformation was more geopolitical and economic than anything. We have the popes in Rome, who were mostly Italian, telling the rest of the Christian West what to do, believe, etc. The popes collected their own taxes from all of Western Christendom when there was no explicit scriptural basis for it - meaning, there isn't a verse saying "I Paul command thee to give a special tithe to Rome" or anything like that. At some point someone is going to question why they're paying the pope taxes when it isn't explicitly stated to do so in the Bible.
I was raised Catholic before becoming Orthodox and somewhere in there I took a gander at the various Protestant branches. The issue I ran into, was that if the Bible is the sole source of all that we believe and do, what did the early Church have to work with during the first four centuries of Christianity when there was no Bible?