Why did Yeshua accept to be crucified and to go through what he did?

It was a sacrifice in the greatest sense of the word. Yeshua came to change the course of Earth, to shift Earth into the process of ascension. Earth and the people on Earth had descended to the lowest extent imaginable, and there was concern that it would remain that way for a very long time, or perhaps Earth would not be able to turn itself around. So Yeshua came to do this work — to turn the evolutionary process and reset it so that Earth could begin its process of return, of ascension, and no longer be stuck in the place of the lowest densities.

The crucifixion was a very essential part of this. The spiritual force that Yeshua had manifested within himself was released into Earth and also into humanity through the crucifixion, allowing a new level of light and love to take root and take hold in this world. This was the most fundamental reason for the crucifixion.