This is not true of all Protestants. I've seen some that downplay Mary's role and I've seen some that are just as gaga over Mary as any Catholic. So please understand that I'm not trying to categorize anyone. That being said this discussion is to talk about one extreme's view of the BVM (blessed virgin mary).
I recently got into a discussion with a guy who made some off handed comment about Mary being on the mother of Jesus. His exact wording was Mary was Jesus's earthly mother that's all. To believe that is to deny the Trinity at worse and at best to downplay Mary.
The Trinitarian belief is that Jesus, God, and the Holy Spirit are one and eternal. They have always been regardless of when Christ's conception took place.
It is also the Christian belief that Jesus was both equally divine and human.
Therefore Mary gave birth to both Jesus's divinity and his humanity. In other words, she also gave birth to God (and the Holy Spirit).
Take that a step further and you can see the logic says that Mary is not only Christ's earthly mother but she is also the Mother of God.
Keep going and you can concede that God is the creator of us all. Therefore Mary gave birth to God who created us so she is also our mother (or grandmother if you want to get technical about that).
And that's why she is so darn important.
But...but...but. I can see the logic train has left some still disagreeing.
Let's look at it from an earthly point of view. I have given birth to two boys. I gave birth to both their soul and their physical body. These are not separate and have (thus far) not been separate since conception. This is part of who they are. To say that I gave birth to HB's soul or Knee's body only is to place a higher value of one over the other (we won't go into if the body's evil for sake of argument it's not). There is not higher intrinsic value of the soul over the body or vice versa. So if one is to say that I gave birth to these children, they would be referring to both parts of them. I gave birth to both HB and Knee's souls and bodies. I am their mother. So I am the mother of both their souls and bodies. Get it?
To use this analogy, Mary gave birth to both Christ's divinity and humanity. They aren't separate and neither holds higher value over the other. To say that Mary is only the early mother of Jesus is to hold Christ's humanity higher over his divinity instead of equally when it comes to his birth. Or that they are somehow separate. And because they are not separate then Mary also gave birth to God. Yes, I'm repeating myself.
But if you knew someone gave birth to say some important figure to you and you ran into them in the airport, you would hold them in high regard by virtue of being the parent of someone you admire. You wouldn't discard their role nor would you say that their mother only gave birth to their body. It wouldn't make sense.
And that's what's so special about Mary and why she is held in high regard. Capisce?