I'll share a few thoughts.

The name "Christian" means "Christ-like".
That's one meaning, but not necessarily a realistic or helpful one to apply to most who profess to be Christians. I would venture that most who call themselves Christian are referring to a belief in Jesus as Son of God and Savior. Being Christ-like may be a desirable attribute or goal for Christians, but I don't believe it is what they are claiming.

Jesus did not lobby Rome to replace Pontius Pilate as procurator. I am certain he did not agree with Roman occupation of his country, yet he did not gather a following in order to make a political statement....Jesus did not carry signs protesting the practice of crucifixion. He did not, with his men, stand near the place of crucifixion saying things like "Where is a sniper when you need one"....
Jesus' role was necessarily different from that of those who follow him, and the setting in which he appeared is different from the setting in which the above-mentioned actions occur. Political protest on his part may well have resulted in the execution of Jesus the man before Jesus the god fulfilled his mission. Said mission was not political, but spiritual in nature. Asking why Christians do things Jesus did not do strikes me as an apples-to oranges comparison.

Still, the answer as to why Christians do some of the things you mentioned would typically be that they believe these are the right things to do bring Man closer to God. Given that plenty of Christians believe that these examples are NOT the right thing to do, one can especially appreciate the wisdom of the U.S. Constitution's and Government's doctrine of separation of church and state.

Extremely few people follow Jesus' example and teachings in basic lifestyle, which would encompass giving away virtually all material goods. Are we ready to ask why most Christians don't do likewise?

Plenty of lousy things have been done in the name of Christ. That's not likely to change, nor is human nature, nor the diverse and sometimes irreconcilable differences of opinion folks have on how to best follow Jesus' teachings and God's will. Most of the questions raised in the opening post strike me as being rooted more in politics than in theology. My advice--find a church that's a good fit for you, where you can be more effective in practicing Christianity as you believe it should be done.