Power in Israel was delicately balanced between the Roman occupiers and the Jewish leaders who were held responsible to control the people or lose their privileges (John 11:48).  The Romans, as well as being invaders and economic beneficiaries of all their conquered territory, saw themselves as benefactors and generously agreed not to violate social customs or religious traditions.  To demonstrate this to the people, Pilate had agreed to release one Jewish prisoner each year.  

From anxiety to desperation: Pilate's voice may have reached a higher pitch as the trap closed around him.  Instead of issuing a right verdict, he thrashes around like a fish in a net and offers himself to the judgement of the crowd; and of all history.  Of course, the discussion about Barabbas was a ploy to avoid the real subject, Jesus (Mark 15:6-8).   Pilate may have hoped the crowd would be on the side of justice and truth, but the angry mob's insistent demand killed truth and obliterated the voice of Pilate's conscience.

The repetition of abuse against Jesus showed that each blow was no accidental slip up; no unintentional insult.  Spitting was not just an objectionable habit - this was the Eastern way to show personal disgust - that the spat-on person was declared rejected (Isaiah 50:6), the lowest of the low.  Even the purple robe was too good for Jesus, in their eyes.  There was no dignity left, no part of His body unstained with blood.  His precious head was not just pierced with thorns, but also battered with poles.  And then they still had to crucify Him.

"What's in it for me?".  Although this is the theme-song of global materialism, it is totally opposite to Jesus' attitude at the cross (Philippians 2:4-8).  His execution was no sanitised or anaesthetised death cell experience; that was not how He planned it.  And, yes, Jesus was fully involved with the Father and the Spirit in planning this crucial moment in history (Acts 2:22-24).  To take the sins of the world, He needed to experience all of His Father's wrath against every sin that had ever been, and would be, committed.