"But this assembly of bishops has no ecclesial or ecclesiastical status whatsoever... It is not a canonical body. It is not an episcopal synod. It has no official place or status in the Church’s essential structure."
They are canonical bodies with ecclesial status. Please see the canons governing them: http://www.vatican.va/archive/ENG1104/__P1L.HTM
"According to Roman Catholic doctrine, it is not essential to the Church’s being and it need not exist. As the saying goes, it may be established for the church’s “well being” (bene esse) while being not at all necessary to the church’s “very being” (esse)."
Is it not Orthodox doctrine that metropolitanates and patriarchates are also not essential? The local diocese and bishop is of divine/apostolic institution and are essential. The metropolitans and patriarchs, while venerable institutions are eccelsial institutions that can be done away with.
I think that Father Hopko's point was not to dispute that the assembly of bishops had any canonical status but that they did not act as a real synod--that is a synod of a local church. In fact, it is the Orthodox understanding that the Roman Church itself is not a synodal body because Her head is a super-bishop (see Saint Cyprian as cited in Father Hopko's article).
As for the Orthodox doctrine, we are organized synodally in accordance with apostolic practice and doctrine. The first principle is that all bishops, no matter what their administrative responsibilities, have the same Apostolic authority and sit on the throne of Peter. The second principle is that the lowest church level that constitutes an ontologically complete church is comprised of a bishop surrounded by his priests, deacons and laity (that is the Laos at the local level). The third principle is that, diocesan bishops have a wide latitude in ruling their dioceses except that they must consult with their administrative superior if their practice is of great importance. The canon that specifies this rule refers to the Metropolitan as the administrative superior, but the canon goes on to say that the Metropolitan cannot do anything without the consensus of his bishops. The fourth principle is that the bishops constitute a Holy Synod, headed by a Patriarch, Metropolitan or Archbishop (the title does not matter--this person is the first among equals and is granted some administrative functions and prerogatives). So, to address your remark: yes, the titles above that of bishop are not that essential but they are useful to distinguish differing administrative responsibilities. Since it does not matter what the administrative leaders are are called, we might as well not change what we have presently. Although, it may be a good thing if the end the title inflation in some Orthodox churches and go back to calling diocesan bishops as bishops.