We must be civilized to the Quran because the Quran is the word of God, the direct word of the Creator that is a guide for life for humans. Facing it is not the same as facing an ordinary book, because its position is sacred and noble. If we are civilized when reading, listening to, or touching it, it means that we respect God who revealed it.
Manners also make it easier for our hearts to accept advice and guidance from its verses. For example, when reading calmly, performing ablution, and full of devotion, the verses will be more penetrating than if read casually. Even scholars say that those who treat the Quran with manners, Allah will glorify it, while those who belittle it will be prevented from its blessings. So manners are not just manners, but a way to maintain the purity of the Quran, while also opening the door to blessings and rewards for us.