Having a specific bishop for a specific rite.
If this does not happen, the specific rite will eventually cease to exist in my opinion.
I can not think of any instances in history where there has successfully been a bishop allowing multiple rites to thrive in the eparchy/archdiocese. One of them eventually suffers from prejudice.
If there is not a canon that allows for it - there needs to be - it is part of our fallen natures.
It is a practical reason, not theological, practical to protect particular culture/nations patrimony.
My opinion is that the Orthodox (byzantine rite) Bishops in Western Europe, US and former western european colonies are at the present time less prejudiced toward the Western rite than the Latin rite Catholic heterodox bishops were toward eastern rite parishes 100 years ago. Though this does not mean prejudice does not exist. It is inevitable, it is partly cultural, partly less education, perhaps even partly revenge for past hurt feelings. It is still necessary to have a western rite orthodox bishop or vicar to oversee them and protect them to an extent.
Over time wounds between eastern/western traditions appear to be healing to an extent, but at the same old issues continue to exist and come around to haunt us. It especially does not help that the western rite heterodox "catholic" or protestant churches appear to be stuck in the malaise of modernist humanist heresies and stuck in opposition toward holy tradition. For if the western heterodox "churches/communities" continue to be as opposed toward holy tradition as they are today, this does not make them look trustworthy or help wounds be able to heal.
As could be observed from the recent reconciliation attempts with the SSPX, the pope changed the writing to make it more acceptable to the SSPX Archbishop, allowing them to be against certain vatican II interpretations, but than the pope sent the letter to the cardinals in the ecclesia dei or congregation of doctrine of faith and they changed the words of the letter so that it says the opposite - thus the SSPX archbishop says something to the tune of "we can not sign this document because it is rewritten to disagree with our position".
""We continue to emphasise that there is a crisis in the Church - the Lefebvrian leader affirmed - The news may have become tiresome because Rome makes it seem as though everything is fine but the very next day we talk to them... And here is what we get from the Secretary of the Congregation for the Faith: "But you know, it's the priests, it's the bishops, it's the Catholic universities: they are full of heresies!" Those were the Secretary of the Congregation for the Faith's very words in June 2009! They know, therefore, that the situation the Church is facing is a very serious one. For them to admit that the Church is infested with heresy is bad enough! But what's worse is that they pretend that everything is fine and dandy. It is disappointing, it is worrying, I admit, but this is the reality"."
It is harder to be sympathetic to western rite within orthodoxy if one considers that all of western christianity (society at large as well) seems to be in a state of crisis.
U-word removed - MK.