We have to keep in mind that this bridge (that he used during ‘Earth Song’
carried a symbolic meaning because it symbolized the border between North and South Korea.
If he used the cherry picker or if he just did not use anything at all, then he would not have conveyed that symbolic meaning that he wanted to get across with the use of that bridge.
That is why, that live segment of his performance is called the ‘Bridge Of No Return’ because that bridge that he used on stage referred to the actual bridge located between North and South Korea for repatriation of prisoners of war (once prisoners chose to cross the actual ‘Bridge Of No Return’, then they would never be allowed to return, even if they later changed their minds).
So, in that regard, I believe that this bridge that he used on stage was a thing that can be considered a necessary addition for that on stage performance and the messages of that performance.