I don't want this tread to be a debate about the status of Mary or an opportunity to attack or defend a traditional theology.
Can we just stick to the question in the OP - why does Mary get little mention in Scripture after Acts 1 ?
Did she have no significant role in the emerging Church ?
There are a lot of things that don't get mentioned much. That Jesus was born of a virgin is only mentioned twice in the New Testament: In the birth narratives of Matthew and Luke. We don't see any mention of St. Joseph at all after Jesus is a grown adult except for those in Nazareth saying, "Isn't this Joseph's kid?"--after that, no mention of Joseph. Most of the Twelve Apostles barely get any mention whatsoever. We know Thomas doubted the Lord's resurrection, but after that he gets no mention. Nathaniel gets mentioned once, Simon the Zealot once. None make an appearance in the Acts. Matthias, who replaced Judas Iscariot, doesn't show up again after getting a brief mention.
That doesn't mean none of them were significant in the early Church. It only means that there was no reason to mention them for the purposes of what the New Testament writers were writing. Luke had no reason to mention Thomas, or Simon the Zealot, or Matthew, or Andrew--after Paul's conversion in the Acts, it's pretty much all about Paul; almost to the point that we ought to maybe call the book "The Acts of the Apostles, but mostly just the Apostle Paul" (that's me making a joke)..
Just because the Acts doesn't record most of the Apostles doing anything, doesn't mean they weren't doing things. Likewise, that we get no direct mention of the Blessed Virgin Mary (outside of the off-the-cuff mention of "born of a woman" by Paul in Galatians) doesn't mean she wasn't involved in the goings-on of the Church. It simply means we don't know, because it wasn't written.
If I write a book detailing the life, trials, and stories about Harriet Tubman, I might mention a lot of people who were involved in the Underground Railroad. But I may not mention everyone, and some might only get a passing reference. But that shouldn't mean that they don't all have their own unique stories to tell or were less important--it's just that the focus of the writing would be on Harriet Tubman. In the same way, the New Testament writers had certain goals and purposes, and they make passing references to people, but don't go on in great detail about everyone--it's just not essential to the points they are trying to convey, or to the particular story/stories they are wanting to tell.
There were probably lots of stories about the other Apostles, either written down and lost, or remembered in the living memory of the churches; which is probably how we have surviving traditions about the Apostles at all. The same is also true of the Virgin Mary, and St. Joseph, and others.
One example: St. Thekla is remembered as one of Paul's missionary companions in a number of traditions that were remembered for centuries by churches throughout the ancient Christian world. Yet, St. Luke makes no mention of her. Was there a St. Thekla at all? Probably. It's also probable that some of the later stories about St. Thekla are embellished to some degree; but there probably was a real St. Thekla, a companion in some of Paul's journeys, and she was important enough to leave a lasting impression in Christian communities in some places, but Luke simply doesn't mention her. Paul probably had a lot of people as part of his entourage during different points of his journeys that never got mentioned, St. Luke even makes a point at several times to remind us of when Paul was mostly alone, where most of his companions had left and it was just him, or just him and one or two other people. Some could argue that Thekla isn't mentioned by Luke because she wasn't important, or maybe she didn't exist, or perhaps because Luke was a misogynist and wanted to erase her legacy: But most likely, Luke just doesn't mention her, and no conclusion beyond that can be reached. Again, same with the many Apostles, or with Mary, or <insert any other person from the New Testament here>.
-CryptoLutheran
