It is not seperation, but rather the joining into a family, a communion of believers.
Perhaps, or is it possible (and I don't mean this to provoke) that Mary has become a substitute for Christ in the minds and hearts of many.
I simply don't think that Catholics expressing a devotion to Mary see it as Protestants do, that they are "taking away" something owed to Christ, or ignoring Him in favor of another. I would be real surprised to find someone devoted to Mary who thought Jesus wasn't necessary.
Then why not express it directly about Jesus?
Because it is an aid to thinking. It is a shorthand. And it is a protection from error. If you know Mary is Theotokos, or "Mother of God" you would never babble on in Nestorian (or other Christological) heresy.
SD
I say a version of the Eastern Christian "Jesus Prayer" that affirms this dogma.
Lord Jesus Christ, Son of God, and Son of Mary, have mercy on me, a sinner.