Mary's glorification of God is not for his benefit. It's so we will be directed toward the source of true joy, hope, life, and salvation. We may get distracted by celebrities and led astray by those who lack character. She is focusing our attention and directing our faith toward the Mighty One who has done great things. She is reminding us that the True God casts down the mighty from their thrones, and fills the hungry with good things. He is truly worth being magnified - not for his ego's sake, but for our faith and devotion.