I am in 100% agreement with you on this. I have a suspicion that the main reason some are unable or unwilling to consider that the name "Mother of God" for Mary, the mother of Jesus Christ, the Incarnate Word, was an unfortunate decision to come down dogmatically on is because, to do so, is to acknowledge that their magesterium may have been wrong or mistaken.
Being conditioned from almost birth that The Church is infallible in all doctrines of faith and morals, is a difficult thing to doubt. All other dogmas could then also be suspect. So much balances on this holding, that to allow in even a shadow of a doubt is to be opened up to the question of "What else did they make a mistake about?". I fully understand the fierce defense and the almost hair-trigger response and objection to any disagreement.
I feel sometimes like the people are expected to defend any and everything their Church states and that they are really expected to, as a matter of status of membership. I puts some in awkward positions and may explain why many are reluctant to even discuss their faith with others.
Thank you so very much for your engaging insight, dear sister in Christ!