It is a problem if you believe that Mary was not truly the mother of God. Then, the incarnation is a lie.
This is such a cultish remark, it is almost blasphemous. First of all, Mary is not the Mother of God. This is a nonsensical statement. Mother's predate their progeny. Mary would have to predate God to be His mother.
Clearly, Mary bore the human body which Jesus took on, but Jesus predated His human body by INFINITY. He likely had made several appearances on earth prior to his "incarnation" as a man. Thus, Mary had an honored place to bear that body, but Jesus did not come into existence at that birth. If this is the Christology of Rome, it is more screwed up than we thought. Please, go ask someone who speaks for Rome...do they actually believe God came into existence after His Mother?
In no way does returning Mary to her normal, human state (a sinner, like all of us, but with a certain job just as Isaiah, or Moses, or Sarah) diminish the incarnation. Once again, a twisted view of the Scriptures.