I have spoke to an Abouna from the American Coptic Orthodox Church on this, (I go to a Modern Baptist Church, my wife is Coptic); and the Abouna’s contention was that the Copts Baptize babies because you as the parent are taking responsibility for their salvation. You are saying that you will bring them up in the church. They are ultra-concerned with the possibility that a baby might die, and not get the blessings which come from Baptism & the sacraments which cone along with it.
This is one of the major issues I have with the Coptic Orthodox practice & have vocalized it with the Abouna & my wife, and have not had a serious theological response. It is my understanding that the whole point of Baptism is understanding that you are in need of salvation and thereby accepting Jesus Christ (the Son of Man / The Word Become Flesh) as your personal Lord & Savior.
The Copts believe that the center of the faith, the focal point is the Eucharist, where you “remember Jesus” by reliving this moment - actually reliving it, and communing with God after you have been purified through the process leading up to the Eucharist.
As Baptist I believe that Baptism should occur in cognitive individuals who understand the decision they are making.