Why is Protestant music allowed into Catholic liturgies?

Because a lot of these liberals, progressives, want to be more like the Protestants. That's why they let in the music. They don't like the old style, stodgy music of yesteryear, the medieval period in the Catholic Church. They don't like Gregorian chant, or they don't like anything that smacks of something old. They are progressive. They think differently than traditionalists and conservatives.