Okay. That's a lot to reply to. It's actually a lot of questions going off in a lot of directions.
First of all, I believe that theology is important and therefore creedal statements are necessary in order to preserve the truth; but I don't believe that everyone needs to have a in-depth knowledge of theology. For the lay people a basic fundamental understanding is necessary by the time one has reached a rational age, but it's not our understanding that saves us, it is God's grace which transcends all of man's understanding. I think the Nicene creed is simple enough to satisfy the laity and theologically terse enough to satisfy the theologian and is important in preserving the faith by defining the truth at a point where the church began to go astray because of the influence of heretics.
Defensiveness and divisiveness are not truly the same things, but one may be the result of the other. And of course, these are not exclusive to Orthodoxy or any component of mankind's society for that matter. Defensiveness is the natural response to an offense, real or perceived, and so many Orthodox people have good cause to feel defensive on account of oppression from occupying nations or also from the assault of evangelicals with there proof texts and aggressive ministries. The great thing about Orthodoxy is, you don't have to be a theologian to be saved, you can just be a simple God-loving individual if you want to and not be ashamed if you don't understand the greater implications of creedal statements. There will always be those who are the defenders of the faith and those who are the body of the faith, those who are the winners of souls and those who are the nurturers of souls - these are the various members of the body and all are important.
The fact remains, that the Nicene creed was responsive, but that doesn't mean that this is a negative thing because it still projects a positive affirmation/proclamation of what we believe. I don't think that the Protestants have it all wrong, but this is not our focus when encountering them, we should focus on what we have in common so as to exude brotherly love. They believe something other than us but it does not mean that they are condemned - but what it comes down to is, when we know better we are compelled to do better.