Most Orthodox Churches in the United States are built by non-Orthodox architechs and builders. It is the responsibility of the Parish Building committee working in tandem with their diocese's bishop to assure that plans meet the minimal requirements for an Orthodox Church. Our Bishop works well with the committees in our diocese and discusses with them the "Orthodoxy" of the building. He is careful to note that it should be a pure model of an Orthodox building, no blending of techniques or styles. I do not know how he would feel about a Modern Orthodox Church, as I have not seen one of that style in our diocese however, I know he does not like the mixing of styles.
As I understand it, the hierarchs approve the building of all permanent facilities in the Orthodox Church, advise who is an "approved" iconographer and style of iconography for the diocese. As a result the "ugly" churches must have been approved prior to their building---the real quaestion might be, Can a Modern Orthodox Church be built in a modern style or must it always be in traditional styling?
For evangelistic purposes, I prefer the traditional style that says to the general public, here is an Orthodox Church meaning, domes, and icons; howveer I am not opposed to a tastefully done modern church building if it inspires the feeling of worshiping in heaven.