They don't pay attention to anything where an acutal celebrattion is in order or where something has already been accomplished. They only put emphasis on things that are yet to come and especially on things having to do with martyrdom or fear inducing events.
They never mention the idea that someone HAD to kill Jesus so that his death would be the sacrafice that bought back the lives of all mankind. If people had simply ignored Jesus and allowed him to carry on or if they all accepted his message....then what. He'd have died of old age and nothing would have been accomplished. The way God supposedly set things up, his sacrificial death was the only way for the human race to be rid of the curse it is under.