I think due to our history since the middle of the 15th century, Orthodoxy has been preoccupied with introspection, establishment of its churches or reestablishment of what it once had.
There are great missionary endeavors in the history of the Orthodox Church; the conversion of the Slavs by the Ecumenical Patriarchate of Constantinople beginning in the 9th century; and the Church of Russia's Far East Missions in Japan and Korea, and of course its holy missionary work in Alaska.
But the scourge of captivity under the Moslem Ottoman Turks forced the church to be introspective, focused on preservation. The Ottoman Empire oppressed all the Ancient Patriarchates, Constantinople, Alexandria, Antioch, and Jerusalem, and the Churches of Romania, Serbia, Bulgaria, Cyprus, and Albania and Greece--which were part of the Ecumenical Patriarchate; likewise, administratively, essentially for the others too. This oppression existed largely from the middle of the 15th century until the early 20th century.
Without elaborating herein, the Ecumenical Patriarchate remains subjugated today in the Republic of Turkey.
Around the time the church was riding itself of the oppression of the Ottoman's, beginning in 1917 Russia and in Georgia, and after WWII, spreading throughout the Eastern European Patriarchates of Romania, Serbia, Bulgaria, and the Church of Albania, these of the largest of the Orthodox Christian populous, were suppressed by the evil of Communism; again, rendering us focused on preservation. And since the fall of Communism (1990 more or less), these churches are focused on rebuilding.
Other than the missionary support provided by the Church of Russia before 1917, thereafter, the administration of the Archdiocese of the Aleutians and North America essentially fell apart. Since the early 1920's, the churches in the Western Hemisphere have been concerned with establishing churches and institutions for themselves.
Although controversial, since the Orthodox Churches involvement in the ecumenical movement in the middle of the 20th century, the church consciously decided not to preach to Trinitarian Christians. It was under this principle that caused the National Council of Churches of Christ (NCCC) to criticize the Evangelical Christian Churches that were proselytizing in Eastern Europe, Ukraine, and the Russian Federation after the fall of Communism, upon reports of its investigatory commissions, which had included Orthodox representatives.
I recently heard Fr. Thomas Hopko comment that the Antiochian Orthodox Christian Archdiocese of North America's acceptance of the Evangelical Orthodox Churches in 1988 was the spark that awakened the Churches of North America to our missionary calling. Only in recent times do we have national offices for church missions.
But, let's remember too, we do have the Orthodox Christian Mission Center (OCMC) doing exemplary work, largely in Africa, but elsewhere too, if I'm not mistaken.
Again, much of our history kept us introspective, but our theology calls us to mission. And that may become more of a prominent aspect of our church as time goes by.