A couple more reasons in addition to the one I posted above.
If your a man and you have a child then offically they would be (using your example) a Coptic Catholic and to be correct you would have to have the Mysteries (Sacraments for you Latins) of Initiation administered in your Church, that would be Coptic, instead of the Latin (even though that is what you like).
You are still bound under your Churches Holy Days and other restrictions according to your Church law and traditions.
For example, the Byzantine Churches do not have all the same Holy Days as the Latin Catholic Church and our Holy Days are never moved to a Sunday. Also Great Lent starts the Sunday evening before the Latin Church’s Ash Wednesday with that whole week being meatless. Also during Great Lent Wednesdays are meatless, not just Fridays.
Another reason is like what a friend of mine is going though now. He is a Latin Catholic who attends, and is registered in, the Melkite parish I attend. He holds the Latin Holy Days as well as our Byzantine ones but that is sort of hard on him but the issue for him is that he wishes to be a deacon, so he much switch Churches, now as the deacon can be married in both the Latin and Byzantine Churches, he will not be faulted for wanting to change Churches to be ordained a married deacon as he would if he had wanted to be a married priest.