First, as the Catechism
points out, the just war doctrine is a doctrine, not just a theory. Second, I don’t think it’s accurate that the conditions of the just war doctrine allow what you say.
CCC 2243 says that a revolt is only justified when there is good hope of success, the resistance won’t cause worse disorders, and all other means of redress have been tried. I don’t think those conditions were met in 1st century Judea. The doctrine is present in the New Testament and in the pre-Nicene Fathers.
source Some of Jesus’s disciples served in the military and St. Cornelius the Centurion is one of the earliest saints who served in an army. Jesus taught the right to armed defense in Luke 22:35-38 and St. Paul used that right to defend himself in Acts 23:12-31. The New Testament teaches that the state has the right to use the sword to defend its people against evildoers in Romans 13:4 and the Book of Revelation mentions that Jesus will “wage war justly” in Rev. 19:11. Pre-Nicene Catholics served in the military in the Theban Legion and the Thundering Legion, and there were Catholic soldiers in service in Alexandria including St. Maurice. Moreover, the pre-Nicene Church Fathers taught that some wars are just and that Catholics can serve in the military.
source
Nine ecumenical councils have spoken in favor of the Church’s just war doctrine, including the Second Ecumenical Council.
I don’t think the Church can give up the just war doctrine because I think it is clearly a part of Church teaching as handed down to us by Jesus, the Apostles, the ecumenical councils, the Fathers of the Church, and the Doctors of the Church. That doesn’t make the just war doctrine flawed. People will always use good things to justify bad things and that doesn’t mean the good things are flawed. People will use the name of God to justify bad things and that doesn’t mean the name of God is flawed, and people will use the Church’s just war doctrine to justify bad things and that doesn’t mean the just war doctrine is flawed. In fact, an explicit part of the Church’s doctrine is that we reject Mutually Assured Destruction. This appears in the encyclical Pacem in Terris paragraphs 110-111 and in Gaudium et Spes paragraph 81. Therefore, those who use the just war doctrine to justify those things are contradicting themselves.