The Immaculate Conception was added "recently?" Take your complaint with St. Ephrem, who lived in the 4th century.
O Virgin most pure, wholly unspotted, O Mary, Mother of God, Queen of the universe, you are above all saints, the hope of the elect and the joy of all the blessed. It is you who have reconciled us with God, you are the only refuge of sinners and the safe harbor of those who are shipwrecked; you are the consolation of the world, the ransom of captives, the health of the weak, the joy of the afflicted and the salvation of all who have recourse to you, and we beg you to have pity on us.
O Virgin Immaculate, Mother of God and my Mother, from your sublime heights turn your eyes of compassion upon me. Filled with confidence in your goodness and knowing full well your power, I beg you to extend to me your assistance in the journey of life, which is so full of dangers for my soul.
In order that I may never be a slave of the devil through sin but may ever live with my heart humble and pure, I entrust myself wholly to you. I consecrate my heart to you forever, my only desire being to love your divine Son, Jesus. Mary, none of your devout servants has ever perished; may I, too, be saved. Amen.
Yes, the I.C. as dogma is recent, 1854. Dogma is what the writer was writing about.
I suspect the problem for Western protestants is the fact that the IC was declared Dogma, not that the concept of the IC in the West is something new. Clearly in the Church the belief in the the sinlessness of the Theotokos is very, very old. Being Westerners, the idea that Panagia was conceived without Original Sin, I suspect, shouldn't cause a problem if indeed they believe in the Incarnational theology of the Church as established by the Fathers and the Councils. For the Orthodox, however, the problem would lie with two ideas. First, Orthodoxy does not accept the Western idea of Original Sin and second, of course, Orthodoxy cannot accept as "dogma" the proclamation, sua sponte, of a pope. That said, of course, Orthodoxy has always, in conformity with the belief of the people and the concesus patrum, proclaimed the sinlessness of the BVM and treated it as dogma, even if a few of the Fathers felt otherwise.
Now, given that so far as I know, Protestantism subscribes to the notion of Original Sin, I cannot see where there can be any valid argument against the dogma on the part of Western Protestants, even in light of the fact that it was proclaimed by a pope, if in fact they also accept the theology of the Incarnation. Personally, I think what we are seeing here is simple anti-Romanism, nothing deeper or more profound than that.
Your assumption is that being created by human sexuality somehow taints a person with sin--which the Orthodox would reject. Original sin is not "passed on" by sexual procreation. I believe, and Agrarian will correct me if I'm wrong, that Mary's sinless state has nothing to do with how she was conceived.