Perhaps some real theologian would have something different to say about this. I’m not one, but I will say what I think about it.
It has been my impression that there is more meaning to the difference than people often attribute to it, and it has to do with a central difference between Protestantism as understood by most Protestants and Catholicism as it should be understood.
For most (but not all) Protestants, the Incarnation is a past event. Jesus was crucified, died, was buried and rose again, and that’s that. It’s rather similar to the belief most Protestants hold that there is a chasm between the living and the dead, which no one crosses into this world, as well as the belief of some (but not all) Protestants that one’s salvation is also a spot on a timeline. “Once saved, always saved” and all that. For Catholics, salvation is a daily struggle in which one (as Jesus put it) “…falls seven times a day…” And to Catholics, each fall is a true fall.
In Catholicism, the sacrifice of the Cross is ongoing; intended by God from all eternity and into all eternity. In God there is no time and His intentions have no “past” or “future”. They’re eternal and always present to Him. The Mass is a true sacrifice, every bit as much as the cross and Calvary. And so, it’s always “in the present”, not a segment on the timeline of history. Jesus is, therefore, as much crucified today as He was 2,000 years ago, and He will always be. The sacrifice is, therefore, vastly greater than we can possibly imagine. Infinitely greater. We can’t comprehend something infinite, but we can symbolize it in limited ways.
Most Protestants do not believe in the Eucharist in the same way Catholics do. For most (but not all) it’s not a true sacrifice in the present, but a commemoration of a past event.
And so, for most Protestants, it’s fitting that the cross be empty. Jesus was crucified in time and the timeline moved on. For Catholics, it’s fitting that Jesus be on the Crucifix because the timeline as to His sacrifice never moves on.