THe substance of my question: Why do Orthodox use the argument of Latinization as an obstacle to unity when Constantinople hellenized the churches on the Roman Frontier?
THAT IS ALL.
I think the problem here is your presumption of hypocrisy.
At one time, uniformity of practice was considered an ideal. I understood this when I was a young man in the Latin church. We were very happy and proud that one could attend a Mass anywhere in the world and it would always be the same! (This was before the ‘you-know-what’ after V-II). We were not taught about the eastern Catholic churches and their unique ritual ractices (that would have been inconvenient, I suppose, considering the main point being stressed). Conformity was prized over diversity.
I bought into this line of reasoning then, but reject it altogether today, do I feel like a hypocrite now? No, I have simply changed my opinion.
The United States government felt exactly the same way when it put the native Americans on reservations. In most reservation schools native language was forbidden, and Christian missionaries (usually Protestant) were given easy access. The idea was that the sooner the ‘Indians’ were able to adopt white American ways, the sooner they would be productive loyal elements of society.
The United States the British Empire had once accepted slavery, and officially sanctioned unequal treatment of large blocs of their own populations. Now we see nations like China doing things like that, and people in Africa doing things like that, and we condemn them for it. Do we feel like hypocrites because our own nations did essentially the same thing in the past?
We
would be hypocrites if we were still doing those things while criticizing others for it.
I think our outlook has changed because our values have changed. We cannot change our historyt, but we can help prevent others from making the same mistakes.
The Roman empire felt that conformity was preferable, but it was somewhat more complex than simply religious ritual conformity. The non-Chalcedonians were not participating in the later church councils and had no influence in them. Some of the councils were mandating church discipline (disciplinary canons), this had a way of making practice more uniform. The law of the empire mandated that everyone
should be at that time with diaphysite Orthodoxy. If one was Orthodox, or converted from Miaphysitism to Orthodoxy in the empire, one would have to accept the canons of the Councils and the disciplines of the patriarchs. This meant that the liturgy of Saint James was rarely served, and the liturgy of Saint Basil/Saint John Chrysostom was commonly served.
There were Helenized Greeks all over the empire for hundreds of years, and these generally supported imperial policies. They saw their nation as the empire itself, not just the region they lived in. These people were happy to conform to imperial mandates, they supported the king. Their neighbors who identified with the local language and culture generally refused to comply with imperial mandates or attend Greek language parishes.
The regional ethnic minorities saw suppression of their local religious traditions as part of a bigger process to rob them of their identities. They were not wrong about that, the empire would have been happy to see everyone become Helenized supporters.
Most Orthodox today would not support the concept of imposing the Greek ritual tradition upon other Orthodox. What has never changed is the need to have a common belief set. It is imperative that everyone agree in doctrine, and I believe that you and your church would agree in principle on that point.
I myself do not advocate turning everyone into Greeks. I would personally love to see a complete restoration of relations with the churches today known as non-Chalcedonians, with concelebration and communion. The empire is dead, and from my perspective it is not relevant.
So what about these Latinizations?
We know about the longstanding policy of Praestantia Titus Latini, an idea that was not connected to a political/economic situation but to a religious ideology. We saw it applied to formerly Orthodox churches and did not like what we saw. This meant that union with the See at Rome became a fearful thing for Orthodox to comprehend.
Rome learned that this was a poor policy which discouraged unity, and has begun to drive it’s own eastern Catholic particular churches to restore themselves. This has been met with dismay by many eastern Catholics, for whom the latinized form of church is all they know.
Many parts of Europe were once eastern and are now Latin, and most people from those areas today have no idea their ancestors were once Orthodox. I list: southern Poland, Czech Republic, Hungary, Slovakia and southern Italy. The policy of Praestantia Titus Latini assured that the theology and spirituality of those people would change as well as their liturgical practices.
I think that if the entire Orthodox church had been taken into union in those bygone years, the See at Rome would have had no reason to reverse it’s policies, and the process of absorption would continue until Orthodox spirituality and theology would be gone.
It is only because the latinization has proven harmful to the goal of unity that the church has seen a need to change. That is perhaps a lesson the empire did not learn in time.
Unfortunately, we can still today read threads started by crypto-latinizers wanting to put amices on altar boys. So the spirit of latinization… the idea that Latin ways are to be preferred… has not altogether died away.
This is a concern for eastern Catholics, who must accept that this kind of person is part of their world and there is no way to keep these people out. For Orthodox, it is just amusing to observe.
If you want to talk about liturgical dominance, then ask the Maronites and other Eastern Catholics. Then we can talk about this.
A very Orthodox thing. 
