During the Mass, particularly in the consecration, the Priest is acting in the person of Christ Himself. Why would I not want to be focused on Christ? Having said that, I go out of my way to focus on the Eucharist during the whole consecration. I watch to see the manner in which it is being treated, handled with reverence, and the manner in which the Priest, Deacons, and alter servers interact and perform their responsibilities during the Liturgy. But, mostly, I am fixated on the Eucharist. All of this helps me greatly to believe in and celebrate the real presence of Christ in the Body and Blood. When the Priest is facing away from me, I cannot see the Eucharist other than select moments when the celebrant holds it up in the air. Hard to focus on the Eucharist when you can’t see it.
I will readily admit there are things would could be improved in the OF of the Mass from the music, abuses, lousy homilies, etc. Heck, I would even be just fine with bringing back alter rails! But the celebrant facing away to me, brings nothing and actually detracts from the liturgy.