From the LDS POV (which, BTW, is not Trinitarian), Jesus made himself a sacrifice for sin. That is, he was sinless and suffered and was killed for our sins, so that we would not have to pay for them if we repent. This worked in several ways.
-He took on, in the Garden of Gethsemane, the pain and suffering of all sin. (This is, I understand, somewhat unique to LDS–that we focus so much on Gethsemane as well as the cross) This was an ‘infinite sacrifice’ – such a huge measure of suffering that it could not be measured and would simply not be bearable by any ordinary mortal who was not divine. He did this voluntarily, but reluctantly, because it wasn’t going to be any fun at all.
-He was then killed, because the sacrifice had to be of a life. Not just any life, but that of the Son of God, who is both human and divine. While on the cross, we believe, the full weight of that suffering he went through in Gethsemane came upon him again, and the sustaining presence of God the Father left him.
So, to the LDS, the scourging and so on is more of a mark of Jesus’ humility and willingness to do this out of love for us than the central part of the Atonement. The central part of the Atonement was the part where he took on all suffering, and was then sacrificed. No one else could have done it, physically or mentally. Sinlessless was not quite enough–as noted, babies and other innocents have died before (and the LDS do not accept the idea of original sin). Suffering was not enough, ‘simple’ crucifixion was not enough. It had to be God who voluntarily suffered everything and died without having broken any law or sinned.
Additionally, when Jesus went through this, he was not omniscient. That is, he was fully experiencing mortality and the veil which separates us from perfect knowledge of the Father operated on him as well. So while he did have a knowledge through faith that he would be fulfilling the sacrifice ordained to him, he still suffered the visceral fear anyone would on coming to that cross.
Since this is a somewhat flippant thread, I can’t say I’m very comfortable discussing this in depth. But I hope that gives you some idea of why we don’t see it as ‘giving up a weekend,’ something that many people might volunteer for.