"Scripture Alone" means relying upon Scripture as the most reliable guide to doctrine, to the exclusion of competing and manmade alternative authorities.
It was presented as the alternative to a corrupted process, you could say. That's what reform normally is--correcting something that's gone awry and returning to the original.
Each of us will have to decide that for ourselves, I guess. However, I have no hesitation in saying that the superstition-ridden and thoroughly politicized and corrupted Medieval Church that, BTW, your EO churches would not reconcile with either, needed reform.
But if someone who has only a dreamy idea of the Middle Ages as a time of lovely Gothic cathedrals and knightly codes of chivalry (and I'm not speaking of you here, in case there's any doubt), he's likely to think that everything was just fine and should have gone on forever. Those people also are unaware that almost all of the key changes that the Protestant churches wanted and instituted have been adopted also by the Roman Catholic Church itself in the years since.
In short, the return to Apostolic standards has my approval.