Antiphonal singing is part of the heritage of the Church.  Have you ever visited a monastery for the Liturgy of the Hours?  The monks recite the psalms antiphonally; in fact, most monastic choirs were designed specifically for that type of prayer.  This is not clerical, it is Catholic.  The idea that the laity should participate in every aspect of the liturgy is a Protestant notion, not a Catholic one.

I do agree, though, that some Glorias are needlessly drawn out.  That's fine for a solemnity or major celebration, but for a Sunday Mass in Ordinary Time, seems a bit much.