I don’t see where … the assumption of Mary being dogma (is) necessary for salvation - so why make (it) mandatory? Teaching is good, but when you make a mandatory “rule” you risk more division, and I can’t see division over things not necessary for salvation.
There are parts of the
Bible that, at first glance, don’t seem to me as necessary for salvation. In fact, argument could be made, and
was made by some early Christians, that having a written “New Testament” was an unnecessary invention. This innovation by the Magisterium was divisive, as was the Magisterium’s decision to exclude the great majority of plausible scriptures.
If you look at a cathedral, it is hard to see how this buttress is necessary, but it may be supporting something else not visible until further analysis. In a play by Shakespeare, it is hard to see why this scene is in there, but the third time you see the play you
now see how it helps set the mood for something else coming up.
But why the definition of the Assumption, in 1950? Here’s my personal IMHO: in the 1960s some Catholic and Protestant writers pushed the idea that Jesus was
only human. They depicted him as a revolutionary, who promoted equality, led the poor against the rich, no supernatural connection at all. Liberation theology.
Other writers depicted Jesus as
only spiritual. They taught he was not an actual physical individual, but a trend, a feeling that existed around a community, about 2000 years ago, to lift aspirations of people; that
spirituality is a goal in itself. The New Age movement.
Perhaps the Assumption dogma reinforces both the supernatural, and physical realities of Jesus. (All that is just my
opinion). Or maybe I am wrong, and it holds up something else that won’t be apparent yet. I do see, now, why it was crucial for the Church to oppose Arianism, though at the time the struggle against it would have seemed divisive and unnecessary, and not needful for salvation.
The best book to explain dogma is “Orthodoxy” by G. K. Chesterton.