The easy answer is that they haven’t really hidden him, and we do have a major elevation–at least one–to prove it.
There is a reaction brewing against priests saying Mass with the Eucharistic elements in full view. Most often the discussion is framed by urging the people and the priest to face the same direction when praying the Mass. To that I usually reply if the altar is between the priest and people, they are facing in the same direction: toward the Lord. Toward Christ is the only direction that matters.
My sense of the change in altar practice after Vatican II was not so the presider could perform for the faithful, as is erroneously suggested. Vatican II argued for more intelligibility in the liturgy, more understanding of it. The problem with ad orientem worship is that the priest obscures the sightlines for the Eucharist. It contributes to a sense of secrecy, a kind of creeping magical gnosticism. The secrecy isn’t good for liturgy; in fact, it damages what the Church tries to accomplish in liturgical formation.
It may be a particular problem for the West today, as much as we associate visually more than experientially. But consider the multiplicity of elevations over time: the faithful wanted to see. “Seeing is believing” is overworked as a cliche, but it contains an important truth. Human beings most often receive God through the senses, sight being the foremost of them.
That said, I can accept that in communities with a deeply intentional spirituality: religious life, TLM parishes, for example, ad orientem worship may be a viable option for Mass. Speaking for myself, it wouldn’t matter that much to me were I to visit or join such a group.
I wish we could put to rest the false notion that non ad orientem facilitates performance. Any priest with poor presidential skills, awkwardness, or ego will draw attention to himself, no matter what the liturgy looks like. One only has to browse through the image sections of any traditionalist liturgy site and take a count. How many images of clergy, usually in very fine vestments? How many of the church architecture? How many of the people? How many full images of the whole Mass?
I can say that in almost forty years of Catholic worship, I don’t pay attention to the priest when I’m praying the Eucharistic Prayer. I focus on the Eucharistic elements, and I’m glad the clergy are behind the altar and out of the way. That’s how most Catholics see it.